On the Origins of the Hijr¯ı Calendar: A Multi-Faceted Perspective Based on the Covenants of the Prophet and Speciﬁc Date

: There has been much speculation as to the type of calendar that was used by the pre-Islamic Arabs and the early Muslim community. The Hijr¯ı calendar is said to have been adopted by ‘Umar b. al-Khat.t.¯ab during his Caliphate despite evidence suggesting that it was instituted as soon as the Prophet emigrated to Mad¯ınah. In this paper, we argue that a number of competing Arabian calendars existed up until 17 AH/AD 638, after which the Hijr¯ı calendar was adopted as the deﬁnitive calendar of the Muslims. We propose that attempts at reconciling dates emanating from different calendars for major events in the Prophet’s life led to miscalculations which subsequently affected the chronology of the s¯ırah . This study ultimately argues that a purely lunar calendar was used by the pre-Islamic Arabs in parallel to a lunisolar calendar, and that speciﬁc dates reported in the covenants of the Prophet and in the historical works could shed new light in reconstructing the chronology of major events in the Prophet’s life.


Introduction
Al-Bīrūnī's (d. 440 AH/1048 CE) Kitāb al-Āthār al-Bāqiyah 'an al-Qurūn al-Khāliyah is perhaps the first major book by a Muslim scholar to conduct an in-depth study of the various calendars. Other than being the most important source available to us on the origins of the pre-Islamic and Hijrī calendars, his work also attempted to verify the accuracy of major historical events by determining whether they matched on more than one calendar. The most important scholarly attempt at reconstructing the pre-Islamic calendar was conducted by Caussin de Perceval, 1 who believed it was based on a system of intercalation that took place every three years. Mahmoud Effendi's study later followed, in which he utilized astronomical data to determine the birth and death dates of the Prophet, the date of the Hijrah, and the year in which the Prophet's son Ibrahīm died. Contrary to Perceval, Effendi concluded based on the calculations which he effected that "the Makkans employed in the fifty years before the Hijrah a calendar that was entirely lunar." 2 Henri Lammens went on to comment that Effendi's efforts had been painstakingly unnecessary. To him, the time periods relayed in the Islamic sources, which include the age of the Prophet at various points in his life, including that of his Companions, represent a purely symbolic topoi of little historical value. According to Lammens, the primitive Arabs could not possibly have maintained any concise record of events, because "the calendar loses its value for these men constantly living in the immutable desert." 3 Other than pointing out discrepancies in the Muslim literature concerning the age of the Prophet, Whenever an embolism was applied, the intercalary month of Adar II would have become the equivalent of the month of nasī' in the Jewish-Arabian calendar. With the passage of time, there would have been a gap between the actual lunar month of Dhū al-H . ijjah and the lunisolar month of Dhū al-Hijja. When the Muslims performed the lesser pilgrimage in the month of Dhū al-Qa'dah 9 AH on the strictly lunar Hijrī calendar, it fell as the month of Dhū al-H . ijjah on the Jewish-Arabian calendar. In 10 AH, the month of Adar II would have been the month of Dhū al-H . ijjah on the Hijrī calendar and the additional month of nasī' on the Jewish-Arabian calendar. The very fact that the Prophet knew that the Farewell Pilgrimage in Dhū al-Hijja 10 AH was the correct date for the pilgrimage, clearly demonstrates knowledge and observance of a lunar calendar alongside a lunisolar Jewish-Arabian calendar.
Another reason why we consider the theory of the Jewish-Arabian calendar having been a mirror of the Jewish calendar is that two of the Jewish pilgrimage months, the Passover which falls in the month of Nisan, and the Tabernacles which falls in the month of Tishri, would have definitively been fixed in the Jewish-Arabian calendar as the sacred months of Muh . arram and Rajab, respectively. Jews who had emigrated to the Arabian Peninsula after the destruction of the First Temple may have differed from those who emigrated there after the destruction of the Second Temple on whether the Jewish calendar ought to be strictly lunar or lunisolar. Jews who believed their festivities should be based on a purely lunar calendar would have eventually came to follow the Prophet. The fast on the 10th of Muh . arram, which would have at some point been the equivalent of the day of Yom Kippur on the strictly lunar calendar, is perhaps one of those Jewish practices which came to be inherited by the Islamic tradition. Needless to say, it appears that there were three pilgrimages whose observance all Arabian Jews agreed upon: the Passover, Tabernacles, and the pilgrimage on the 9th of Dhū al-H . ijjah, which may have been instituted Religions 2021, 12, 42 5 of 21 to commemorate the destruction of the First Temple. 19 As there is in principle no harm in the system of intercalation, we consider the Qur'ān's condemnation of the nasī' to follow our following interpretation of Q9:37: The nasī' is an increase in unbelief by which those who have disbelieved are further led astray. They render the shedding of blood permissible during the month of nasī' in one embolismic year and render the month of nasī' sacred in another embolismic year. When they render the month of nasī' sacred in one of the embolismic years, they in turn profane one of the sacred months [either Muh . arram, Rajab, Dhū al-Qa'dah, Dhū al-H . ijjah] to make the total number of months during that embolismic year in which bloodshed is prohibited four months. In that way they have made permissible what Allāh has prohibited [i.e., the profaning of one of the sacred months]. Pleasing to them is their evil deeds, and Allāh does not guide the disbelieving people.
As the month of Muh . arram would have coincided with the month of nasī', the intercalary month that was added during the embolismic year was either called S . afar al-Awwal or S . afar al-Ākhir. The nasī' would therefore have been the addition of the intercalary month along with the commutation of one of the sacred months to the intercalary month. Once one of the sacred months had been commuted to the intercalary month, the Quraysh could declare war during that sacred month and thus render it profane. In light of this, al-Majlisī reports this very interesting tradition which cannot be found in any of the Sunni books of Qur'ānic exegesis: The reason behind the revelation of the verse stating that "the nasī' is an increase in unbelief [Q9:37]" is as follows: A man of the tribe of Kinānah used to proclaim during the H . ajj season: "I have made the shedding of blood lawful for those who belong to the tribes of T . ay' and Khath'am in the month of Muh . arram. I have hereby commuted the sacred month (ansā'tuhu) to the month of S . afar." In the next [embolismic] year he would say: "I have made [the shedding of blood] lawful in the month of S . afar and commuted the sacred month (ansā'tuhu) to the month of Muh . arram." 20 The commutation of a sacred month to another in order to justify a declaration of war during an embolismic year was, in all likelihood, the notion of the nasī' which was condemned by the Qur'ān.

The Establishment of the Hijrī Calendar
Al-Bīrūnī explains how the pre-Islamic Arabs were in the habit of keeping a number of competing calendars and would institute a new calendar whenever a significant event would occur. He lists as examples the year when the Ka'bah was built by the prophets Abraham and Ishmael; the year when 'Amr b. Lu'ay became chief of the Arabs; the Year of Treason; and the Year of the Elephant. Evidence of this was brought forth by Michael Lecker in his important study on a pre-Islamic deed of endowment from Marzūqī's Kitāb al-Azminah wa al-Amkinah which was inscribed "thirty five years after the Year of the Elephant." 21 Al-Bīrūnī goes on to explain how four calendars were instituted by the Quraysh during the Prophet Muh . ammad's lifetime. The major events that led to the start of these calendars are: 1) the year of the sacrilegious war; 2) the year when the confederacy of al-Fud .ū l was established; 3) the year of the death of H . ishām b. al-Mughīrah al-Makhzūmī; Religions 2021, 12, 42 6 of 21 and 4) the year of the reconstruction of the Ka'bah through the arbitration of the Prophet. 22 An event as important as the Hijrah would have certainly led to the establishment of a new calendar, and a tradition in al-T . abarī confirms this when it states: "When the Prophet came to Madīnah, which was in Rabī' al-Awwal, he ordered the establishment of the calendar." 23 In a recent study of 'Papyrus Louvre inv. J. David-Weill 20' from early Muslim Egypt, Mehdy Shaddel concluded that its "enigmatic phrase snh qad .ā ' al-mu'minīn" should be understood as "the year according to the reckoning of the believers." 24 Based on the testimony of this phrase, Shaddel argues that "What the early Muslims had in mind was apparently the beginning of their polity, which in their view was the dawn of a new age that witnessed the establishment of God's rule (amr allāh) on earth, hence the reference to it in our papyrus as 'the year per the reckoning of the believers.'" 25 The epoch of the Muslim calendar was, according to Shaddel, "in all likelihood, originally meant to count the years from Muh . ammad's foundation of a new community and polity at Medina, a momentous event that the early Muslims conceived of as the dawn of a new age." 26 Hence, the Hijrah must have led to the establishment of the Hijrī calendar on a strictly lunar basis as soon as the Prophet emigrated to Madīnah. 27

Specific Date Verification
Specific Date Verification examines the specific dates recorded for a particular event in the Prophet's life by assuming that the day of the week and month are accurate, but the year not necessarily so due to miscalculations in the year date. Hamidullah was the first to note that discrepancies in reporting a particular event in different years was not because of a difference of opinion as to whether or not the event occurred in different year dates, but rather due to differences in calculations. He lists as an example the raid of Banū Must . aliq and notes how Mūsā b. 'Uqbah reported that it occurred in 4 AH; al-Wāqidī in 5 AH; and Ibn Ish .ā q in 6 AH. Hamidullah reconciles these three different opinions by postulating that the early biographers differed in their calculation of the Hijrah: some calculated it in the year of the pledge of 'Aqaba, others in the year of the Prophet's emigration, and others still in the first year after his emigration. 28 Hamidullah's main premise, as we shall argue, is correct, but he unfortunately never developed it as an alternative to his theory of the Hammurabian calendar being the basis of the Quraysh calendar. Hamidullah noticed how the Islamic sources record "not only the date but also the day" 29 of particular events in the Prophet's life, and how the "dates given in extant concordances do not tally." 30 Hamidullah argued that the reason for this is because the Prophet was using a lunisolar calendar until 10 AH. Ironically enough, Hamidullah did not at any point entertain the possibility that the Prophet was using a lunar calendar as soon as he arrived in Madīnah, and that the reason why there may have been discrepancies in tallying the days of the week is because-as he himself had argued-there may have been inconsistencies in how the year dates were calculated.

pecific Date Verification
Specific Date Verification examines the specific dates recorded for a particular event he Prophet's life by assuming that the day of the week and month are accurate, but the r not necessarily so due to miscalculations in the year date. Hamidullah was the first ote that discrepancies in reporting a particular event in different years was not because difference of opinion as to whether or not the event occurred in different year dates, rather due to differences in calculations. He lists as an example the raid of Banū sṭaliq and notes how Mūsā b. 'Uqbah reported that it occurred in 4 AH; al-Wāqidī in H; and Ibn Isḥāq in 6 AH. Hamidullah reconciles these three different opinions by tulating that the early biographers differed in their calculation of the Hijrah: some calated it in the year of the pledge of 'Aqaba, others in the year of the Prophet's emigra-, and others still in the first year after his emigration. 28 Hamidullah's main premise, as we shall argue, is correct, but he unfortunately never eloped it as an alternative to his theory of the Hammurabian calendar being the basis he Quraysh calendar. Hamidullah noticed how the Islamic sources record "not only date but also the day" 29 of particular events in the Prophet's life, and how the "dates en in extant concordances do not tally." 30 Hamidullah argued that the reason for this ecause the Prophet was using a lunisolar calendar until 10 AH. Ironically enough, Haullah did not at any point entertain the possibility that the Prophet was using a lunar ndar as soon as he arrived in Madīnah, and that the reason why there may have been crepancies in tallying the days of the week is because-as he himself had arguedre may have been inconsistencies in how the year dates were calculated. As specific dates for events in the Prophet's life have mainly been recorded in three rks, namely al-Wāqidī's (d. 207/823 CE) Kitāb al-Mag̱ hāzī;  AH/559 CE) Kitāb alḥabbar, we will use these to build on Hamidullah's initial observation. The specific veration of dates will subsequently entail checking the day of the week and month using ndar converters to determine the actual year dates of these events on the official Hijrī ndar. A good book which has reported an accurate arithmetical record of the week day for first day of every Hijrī month along with its Julian equivalent until October 1582 CE, r which it adopts the Gregorian calendar, is Kitāb al-Tawfīqāt al-Ilhāmiyyah by contested by Mathieu Tillier and Naïm Ventehieghem. One of the dates which they record is illards Marriott Library at the University of Utah entitled 'P. Utah 520' which has a specific date al 57 AH, and which also bears the expression "snh qaḍāʾ al-muʾminīn." If this expression was a the Hijrī calendar as Tillier and Ventehieghem propose, then how come the specific date conlendar is accurate, returning as Monday 26 January AD 677? If anything, this is evidence that . See (Tillier and Ventehieghem 2019, pp. 148-88).
al-mu VIEW 6 of 22 understood as "the year according to the reckoning of the believers." 24 Based on the testimony of this phrase, Shaddel argues that "What the early Muslims had in mind was apparently the beginning of their polity, which in their view was the dawn of a new age that witnessed the establishment of God's rule (amr allāh) on earth, hence the reference to it in our papyrus as 'the year per the reckoning of the believers. '" 25 The epoch of the Muslim calendar was, according to Shaddel, "in all likelihood, originally meant to count the years from Muḥammad's foundation of a new community and polity at Medina, a momentous event that the early Muslims conceived of as the dawn of a new age." 26 Hence, the Hijrah must have led to the establishment of the Hijrī calendar on a strictly lunar basis as soon as the Prophet emigrated to Madīnah. 27

Specific Date Verification
Specific Date Verification examines the specific dates recorded for a particular event in the Prophet's life by assuming that the day of the week and month are accurate, but the year not necessarily so due to miscalculations in the year date. Hamidullah was the first to note that discrepancies in reporting a particular event in different years was not because of a difference of opinion as to whether or not the event occurred in different year dates, but rather due to differences in calculations. He lists as an example the raid of Banū Musṭaliq and notes how Mūsā b. 'Uqbah reported that it occurred in 4 AH; al-Wāqidī in 5 AH; and Ibn Isḥāq in 6 AH. Hamidullah reconciles these three different opinions by postulating that the early biographers differed in their calculation of the Hijrah: some calculated it in the year of the pledge of 'Aqaba, others in the year of the Prophet's emigration, and others still in the first year after his emigration. 28 Hamidullah's main premise, as we shall argue, is correct, but he unfortunately never developed it as an alternative to his theory of the Hammurabian calendar being the basis of the Quraysh calendar. Hamidullah noticed how the Islamic sources record "not only the date but also the day" 29 of particular events in the Prophet's life, and how the "dates given in extant concordances do not tally." 30 Hamidullah argued that the reason for this is because the Prophet was using a lunisolar calendar until 10 AH. Ironically enough, Hamidullah did not at any point entertain the possibility that the Prophet was using a lunar calendar as soon as he arrived in Madīnah, and that the reason why there may have been discrepancies in tallying the days of the week is because-as he himself had arguedthere may have been inconsistencies in how the year dates were calculated.
As specific dates for events in the Prophet's life have mainly been recorded in three works, namely al-Wāqidī's (d. 207/823 CE) Kitāb al-Mag̱ hāzī; Ibn Sa'd's (d. 230 AH/845 CE) al-Ṭabaqāt al-Kubrā'; and Muḥammad b. Ḥabīb al-Baghdādī's (d. 245 AH/559 CE) Kitāb al-Muḥabbar, we will use these to build on Hamidullah's initial observation. The specific verification of dates will subsequently entail checking the day of the week and month using calendar converters to determine the actual year dates of these events on the official Hijrī calendar.
A good book which has reported an accurate arithmetical record of the week day for the first day of every Hijrī month along with its Julian equivalent until October 1582 CE, after which it adopts the Gregorian calendar, is Kitāb al-Tawfīqāt al-Ilhāmiyyah by e been contested by Mathieu Tillier and Naïm Ventehieghem. One of the dates which they record is e J. Willards Marriott Library at the University of Utah entitled 'P. Utah 520' which has a specific date l-Awwal 57 AH, and which also bears the expression "snh qaḍāʾ al-muʾminīn." If this expression was a er than the Hijrī calendar as Tillier and Ventehieghem propose, then how come the specific date conivil Calendar is accurate, returning as Monday 26 January AD 677? If anything, this is evidence that orrect. See (Tillier and Ventehieghem 2019, pp. 148-88).
minīn." If this expression was a reference to a calendar other than the Hijrī calendar as Tillier and Ventehieghem propose, then how come the specific date conversion on the Standard Civil Calendar is accurate, returning as Monday 26 January AD 677? If anything, this is evidence that Shaddel's conclusions are correct. See (Tillier and Ventehieghem 2019, pp. 148-88). 28 (Hamidullah 1965, p. 57). abbar, we will use these to build on Hamidullah's initial observation. The specific verification of dates will subsequently entail checking the day of the week and month using calendar converters to determine the actual year dates of these events on the official Hijrī calendar.
A good book which has reported an accurate arithmetical record of the week day for the first day of every Hijrī month along with its Julian equivalent until October 1582 CE, after which it adopts the Gregorian calendar, is Kitāb al-Tawfīqāt al-Ilhāmiyyah by Muh . ammad Mukhtār Bāshā published in 1311 AH/ c. a. 1893 CE. 31 Nowadays there a number of Hijrī calendar converters which use computational algorithms, the most accurate being the 'Standard' algorithm devised by Edward Reingold and Nachum Dershowitz in their book Calendrical Calculations.
The lunar year comprises of 354 days, but in a 30 year cycle, the lunar year is made up of 355 days on 11 occasions. This means that an extra day must be added 11 times every 30 years. Reingold and Dershowitz' algorithm therefore adds an extra day to the month of Dhū al-H . ijjah so that it comprises of 30 days instead of the usual 29 days during the following years in a 30 year cycle: years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26, and 29. 32 Furthermore, Reingold and Dershowitz' algorithm calculates the 1st of Muh . arram 1 AH as Friday 16 July AD 622, which is the 'civil' epoch, meaning that their calendar can be labelled as the 'Standard Civil Calendar'. 33 The 'astronomical' calendar on the other hand begins a day earlier and regards the 1st of Muh . arram 1 AH as Thursday 15 July AD 622. The reason being is that, like the Jewish calendar, the new day in the Islamic calendar begins at sunset, not after midnight. The 'Standard Astronomical Calendar' 34 therefore applies the same algorithm as the 'Standard Civil Calendar' except that the Hijrī date, along with its Julian equivalent, is one day earlier.
Though the Standard Astronomical and Civil Calendars have been used in this paper, we have also consulted the 'Kuwaiti' and 'Fāt . imīd' algorithms. 35 The Kuwaiti algorithm adds an extra day to the month of Dhū al-H . ijjah in the 15th rather than in the 16th year of the 30 year lunar cycle. As for the 'Fāt . imīd' algorithm, it adds an extra day to the month of Dhū al-H . ijjah in the 8th, 19th and the 27th years of the 30 year lunar cycle instead of the 7th, 18th and 26th years as per the Standard algorithm. We will always specify whether a date returns accurately based on the Standard Astronomical Calendar (SAC) or the Standard Civil Calendar (SCC). 36 The methodology of Specific Date Verification does of course possess a number of flaws. To begin with, one would expect a writer to occasionally make a mistake when recording a specific day of the week or month when writing his historical works, and so one recorded date can neither conclusively prove nor disprove the occurrence of a particular historical event for a particular year. Secondly, the Prophet's biographers did not always agree on the specific date, let alone the month or the year when certain events occurred in his life. Thirdly, the conversion of Hijrī dates to the Julian calendar on the SAC and SCC always bears a one-day margin of error which can open the door to speculation. Fourthly, calendar converters assume particular months to always be 29 or 30 days and do not take into consideration natural phenomenon which means that due diligence needs to be applied when reverting to the methodology of Specific Date Verification. 31 See (Bāshā 1311). 32 (Reingold and Dershowitz 2018, pp. 105-10). 33 See (Fourmilab Calendar Converter n.d.). This is most reliable calendar converter for the SCC. 34 36 We have consulted the 'Kuwaiti' and 'Fāt . imīd' algorithms for this paper but have not referred to them for any calendrical date conversions. See (Keisan Online Calculator 2020).
Religions 2021, 12, 42 8 of 21 The event of the Farewell Pilgrimage which we have briefly touched upon is a case in point. According to SAC, the 9th of Dhū al-H . ijjah 10 AH returns as Friday 6 March AD 632 which is the correct day of the week according to all available reports, while on the SCC it returns as Saturday 7 March AD 632, reflecting a one-day margin of error which we are bound to encounter when dealing with date conversions. Yet, despite this shortcoming, Specific Date Verification can provide us with reliable results when more than one specific date has been recorded for a particular historical event, especially when the data is repeatable and quantifiable, thus rendering the verification of the event being analyzed all the more credible.
If we continue our examination of the Farewell Pilgrimage, we find that its historical dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-H . ijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-H . ijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-H . ijjah and Sunday 4 Dhū al-H . ijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the H . ajj was to take place was Thursday 1 Dhū al-H . ijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-H . ijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-H . ijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāt . ima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of H . ammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads:

1.
In the days of the Servant of Allāh Mu Religions 2020, 11, x FOR PEER REVIEW 8 of 22 we are bound to encounter when dealing with date conversions. Yet, despite this shortcoming, Specific Date Verification can provide us with reliable results when more than one specific date has been recorded for a particular historical event, especially when the data is repeatable and quantifiable, thus rendering the verification of the event being analyzed all the more credible.
If we continue our examination of the Farewell Pilgrimage, we find that its historical dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: 1. In the days of the Servant of Allāh Muʿ āwiyah (abdalla Maavia), Commander 2. of the Believers (amēra almoumenēn), the hot baths of the 3. people there were saved and rebuilt 4. by 'Abdullāh son of Abū Hāshim (Abuasemos), the 5. governor, on the fifth of the month of December, 6. on the second day [of the week], in the sixth year of the indiction, 7. in the year seven-hundred and twenty-six of the colony, according to the Arabs (kata Arabas) the forty-second year, 8. for the healing of the sick, under the care of Joannes, 9. the official of Gadara. 39 37 (al-Wāqidī, 1990, vol. 2, p. 131 The inscription bears a specific date: the second day of the week is a Monday and the 6th year of the indiction, year 726 of the colony, is AD 662. When we verify the date on the SCC, we find that Monday 17 Sha'bān 42 AH does accurately return as Monday 5 December AD 662. Another inscription discovered in Jerusalem commemorating the capitulation of the Holy City, and which according to Moshe Sharon is "probably one of the oldest inscriptions hitherto uncovered," 40 is even more telling. It reads: 1.
In the name of Allāh, the Most Gracious, the Most Merciful 2.

4.
The protection of Allāh and the security of His messenger (dhimmat Allāh wa d . amān rasūlihi) 5.

Its scribe is Mu
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: āwiyah . . . 9.
The year thirty-two. 41 The parallels between this inscription and the covenants are astonishing. The statement that the people of Jerusalem have been granted "the protection of Allāh and the security of His messenger," the presence of witnesses, Mu came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Th day." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH re accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on SAC.
We here have four specific dates, albeit on two different calendar converters, w means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 d a natural irregularity not accounted for in the algorithms. The specific dates therefore firm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'da AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the m when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632 of these specific dates align themselves to the Julian calendar for the year 10 AH, val ing the accuracy of the dates reported in the historical works for this particular even There are other events in the Prophet's life which have more than one specific attached to them and which we have recorded in Appendix A Table A1. We will reve these in the article to identify the precise dates of the Hijrah, the Battle of Badr, an explain the early dating of the covenants. We will also examine the events reported i year the Prophet passed away such as his last illness, the expedition he ordered ag the Byzantines, and Fāṭima's death to offer different possibilities for the year in whic died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is atte in an inscription found in the restored baths of Ḥammat Gader which lie approximat kilometers east of the southern end of the Sea of Galilee. The inscription, preceded cross, reads: 1. In the days of the Servant of Allāh Muʿ āwiyah (abdalla Maavia), Commander 2. of the Believers (amēra almoumenēn), the hot baths of the 3. people there were saved and rebuilt 4. by 'Abdullāh son of Abū Hāshim (Abuasemos), the 5. governor, on the fifth of the month of December, 6. on the second day [of the week], in the sixth year of the indiction, 7. in the year seven-hundred and twenty-six of the colony, according to the Arabs (kata Arabas) the forty-second year, 8. for the healing of the sick, under the care of Joannes, 9. the official of Gadara. 39 37 (al-Wāqidī, 1990, vol. 2, p. 131). 38 (Ibn Kathīr,vol. 4,p. 239). 39 See (Hirschfeld and Solar 1981, pp. 203-4;Green and Tsafrir 1982, pp. 94-95). The authors' translation relied on the translat of the website Islamic Awareness. See (Islamic Awareness 2007).
āwiyah as scribe, and a year date at the end all conform to how the covenants were written. Our two inscriptions therefore support the view that the Hijrī calendar was instituted by the Prophet, and that the Hijrī dates found in the covenants accurately reflect the specific date when they were written.

The Dating of the Covenants
The Prophet's Covenant with the Christians of the World, which was written by Mu'āwiyah on Monday 29 Rabī' al-Ākhir 4 AH, has been extensively documented through a series of manuscripts. It is one of those rare covenants which has the specific date of the week appended to it and when we apply Specific Date Verification, we find that it accurately returns as Monday 7 October AD 625 on the SAC. This is a strong piece of evidence for its authenticity as it is highly unlikely that Christians unfamiliar with the Hijrī calendar would have forged a document of this nature by being correct to the day of the week. We were able to find eight transmissions of this covenant with the accurate date appended to it.

1.
MS 358 in the Matenadaran, in Armenia, is a 17th century copy of the Covenant with the Christians of the World which has been extensively studied by Dr. Gayane Mkrtumyan from Yerevan State University. 42 2.
The Monastery of St. George al-H . umayra in Syria had on public display a copy of the Covenant with the Christians of the World, dating from Ottoman times, which pilgrims could view but which was removed to a safe location following the tragic events that have unfolded in Syria. The text of this covenant was brought to light by Dr. John Andrew Morrow in the second volume of his work Islām and the People of the Book. 43 3.
GAMS (Sbath) 1123 at the Hill Museum & Manuscript Library is undated but probably stems from the 19th century. 39 See (Hirschfeld and Solar 1981, pp. 203-4;Green and Tsafrir 1982, pp. 94-95). The authors' translation relied on the translation of the website Islamic Awareness. See (Islamic Awareness 2007). 40 (Sharon 2018, p. 109). 41 (Sharon 2018, p. 101). For online information about the inscription, see (Islamic Awareness 2020). 42 See (Mkrtumyan 2015, pp. 8-25). We would like to give special thanks to Dr. Mkrtumyan for having provided us with a copy of the covenant for us to analyze. 43  All of the recensions of the Covenant with the Christians of the World agree on the date despite the slight variations in wording. The Sionita and the St. George al-H . umayra recensions read "yawm al-athnayn tamām arba that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads:  (al-Wāqidī, 1990, vol. 2, p. 131). 38 (Ibn Kathīr,vol. 4,p. 239). 39 See (Hirschfeld and Solar 1981, pp. 203-4;Green and Tsafrir 1982, pp. 94-95). The authors' translation relied on the translation of the website Islamic Awareness. See (Islamic Awareness 2007).
at ashhur min al-sanah al-rābi that the Prophet departed from Madīnah "on Saturday, five n Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find Qa'dah 10 AH returns as Saturday 22 February AD 632 on t Kathīr commented that the Prophet arrived in Makkah in the y age "on the morning of the fourth of Dhū al-Ḥijjah. That was came, at dawn, because the first day of Dhū al-Ḥijjah that year day." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 D accurately as Thursday 27 February and Sunday 1 March AD SAC.
We here have four specific dates, albeit on two different c means that the month of Dhū al-Qa'dah in the year 10 AH was a natural irregularity not accounted for in the algorithms. The s firm that the event of the Farewell Pilgrimage began on Satu AH/22 February AD 632 when the Prophet left Madīnah; that when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 1 that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijja and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 1 of these specific dates align themselves to the Julian calendar f ing the accuracy of the dates reported in the historical works f There are other events in the Prophet's life which have m attached to them and which we have recorded in Appendix A these in the article to identify the precise dates of the Hijrah, explain the early dating of the covenants. We will also examine year the Prophet passed away such as his last illness, the exp the Byzantines, and Fāṭima's death to offer different possibiliti died.
ah min alhijrah bi-l-Madīnah;" 50 GAMS 1123 reads "yawm al-athnayn li-tamām arba that the Prophet departed from Madīnah "on Saturday, five nigh Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find th Qa'dah 10 AH returns as Saturday 22 February AD 632 on the Kathīr commented that the Prophet arrived in Makkah in the year age "on the morning of the fourth of Dhū al-Ḥijjah. That was a S came, at dawn, because the first day of Dhū al-Ḥijjah that year wa day." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū accurately as Thursday 27 February and Sunday 1 March AD 63 SAC.
We here have four specific dates, albeit on two different cale means that the month of Dhū al-Qa'dah in the year 10 AH was 29 d a natural irregularity not accounted for in the algorithms. The spec firm that the event of the Farewell Pilgrimage began on Saturda AH/22 February AD 632 when the Prophet left Madīnah; that the when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 A that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 1 and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 A of these specific dates align themselves to the Julian calendar for t ing the accuracy of the dates reported in the historical works for th There are other events in the Prophet's life which have more attached to them and which we have recorded in Appendix A Tab these in the article to identify the precise dates of the Hijrah, the explain the early dating of the covenants. We will also examine th year the Prophet passed away such as his last illness, the expedi the Byzantines, and Fāṭima's death to offer different possibilities f died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the ear in an inscription found in the restored baths of Ḥammat Gader wh kilometers east of the southern end of the Sea of Galilee. The ins cross, reads:  (Ibn Kathīr,vol. 4,p. 239). 39 See (Hirschfeld and Solar 1981, pp. 203-4;Green and Tsafrir 1982, pp. 94-95). The authors' translation of the website Islamic Awareness. See (Islamic Awareness 2007).
at ashhur min al-sanah al-rābi dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: ah min hijraht al-Madīnah;" 51 the copy in the Greek Orthodox Patriarchate of Jerusalem and that documented by Father Gabriel Akyüz reads "yawm al-athnayn li-tamām arba yzed all the more credible.
If we continue our examination of the Farewell Pilgrimage, we find that its historical ating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, at the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū ala'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū ala'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn athīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrime "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime me, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursay." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return curately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the C.
We here have four specific dates, albeit on two different calendar converters, which eans that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, natural irregularity not accounted for in the algorithms. The specific dates therefore conrm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 H/22 February AD 632 when the Prophet left Madīnah; that the first date of the month hen the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; at the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; d that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All these specific dates align themselves to the Julian calendar for the year 10 AH, validatg the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date tached to them and which we have recorded in Appendix A Table A1. We will revert to ese in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to plain the early dating of the covenants. We will also examine the events reported in the ar the Prophet passed away such as his last illness, the expedition he ordered against e Byzantines, and Fāṭima's death to offer different possibilities for the year in which he ied.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 lometers east of the southern end of the Sea of Galilee. The inscription, preceded by a oss, reads: In the days of the Servant of Allāh Muʿ āwiyah (abdalla Maavia), Commander of the Believers (amēra almoumenēn), the hot baths of the people there were saved and rebuilt by 'Abdullāh son of Abū Hāshim (Abuasemos), the governor, on the fifth of the month of December, on the second day [of the week], in the sixth year of the indiction, in the year seven-hundred and twenty-six of the colony, according to the Arabs (kata Arabas) the forty-second year, for the healing of the sick, under the care of Joannes, the official of Gadara. 39 pp. 203-4;Green and Tsafrir 1982, pp. 94-95). The authors' translation relied on the translation ss. See (Islamic Awareness 2007).
at ashhur min al-sanah al-rābi alyzed all the more credible.
If we continue our examination of the Farewell Pilgrimage, we find that its historical dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: when in fact the actual date was '9 AH'. 56 The evidence for this comes from al-Balādhurī's recension of the Treaty, which reads at the end "it was written by 'Alī b. Abū T .ā lib in 9 AH." 57 When we apply a Hijri-Julian conversion we find that 3 Ramad .ā n 9 AH returns as Friday 14 December AD 630 on the SCC. By transposing the year date of 9 AH to 5 AH, we find that the day of the week falls on a Friday, making it highly unlikely that the original document was forgery. The dating of the covenants and the inscription of H . ammat Gader therefore place the first year of the Hijrah on the official Hijrī calendar as having begun either on Thursday or Friday 1 Muh . arram 1 AH/15 or 16 July AD 622.

The Prophet's Day Was a Monday
When a Bedouin asked the Prophet what his opinion was about fasting on a Monday, he replied to him "This is the day in which I was born and the day in which the Qur'ān was first revealed." 58 The importance of Monday is stressed by Ibn 'Abbās in another report: "The Messenger of Allāh was born on a Monday, he became a prophet on a Monday, he emigrated from Makkah on a Monday, he arrived in Madīnah on a Monday, he died on a Monday, and he lifted the black stone [when the Ka'bah was being reconstructed] on a Monday." 59 Another tradition on the authority of Jābir b. 'Abdullāh and Ibn 'Abbās states: "The Messenger of Allāh was born in the Year of the Elephant on Monday 12 Rabī' al-Awwal. It was on that same day that his ascension to heaven took place, that he emigrated to Madīnah, and the day in which he died." 60 Rather than disregarding all of these traditions as mythical, we will here attempt to determine whether there is any truth to them.

The Prophet's Birth
Al-T . abarī provides the following report about the Prophet's birth: The birth of the Messenger of God took place during the reign of Kisrā Anūsharwān, in the year when Abrahah al-Ashram Abū Yaksūm marched against Mecca with the Abyssinians, bringing with him the elephant, having the intention of demolishing the Holy House of God. It happened after forty-two years of Kisrā Anūsharwān's reign had elapsed. 61 As Khosrow I's reign began on 18 August AD 531, 62 Abraha's entry into Makkah would have been in AD 573 according to the solar Julian calendar. However, according to the purely lunar calendar, the 18 August AD 531 is the equivalent of 17 Rabī' al-Rabī' al-Ākhir 93 BH on the SCC. When we add 42 lunar years, the year that returns is 17 Rabī' al-Ākhir 51 BH which is the equivalent of 17 May AD 572 on the SCC. This was the Year of the Elephant, for which Ibn 'Abd al-Barr provides us the following specific dates: Al-Khawārizmī Muh . ammad b. Mūsā said: "The arrival of the elephant in Makkah along with its companions was 13 nights having passed in the month of Muh . arram." Others also said the same, but he added that this was on a Sunday. 56 For a similar conclusion see (El-Wakil 2016, p. 311). 57 (al-Balādhurī 1987, p. 81). 58 (Muslim 2017, p. 483). Also see (al-T . abarī 1999b, vol. 6, p. 62). 59 (Ibn Kathīr 1990, vol. 2, pp. 259-60). Though we have reverted to the Arabic for our translation, to consult the English text, see (Ibn Kathīr 2000, vol. 1, p. 141). 60 (Ibn Kathīr 2000, vol. 1, p. 142); (Ibn Kathīr 1990, vol. 2, p. 260). 61 (al-T . abarī 1999a, vol. 5, p. 266). The date of Abraha's expedition to Makkah has also been placed to AD 552 which would imply he was deceased by the time the Prophet was born. See (Kister 1965, p. 428). A report in Ibn Kathīr states that the Prophet was born 23 [lunar] years "after the attack on Mecca by the troops with elephants." See (Ibn Kathīr 2000, vol. 1, p. 143). If correct this would place the Year of the Elephant in AD 549. Mohammed Lamsiah has argued that the story of the elephant in the Qur'ān recounts the defeat of Khosrow I by his general Vardan after he rebelled against him. See (Lamsiah 2017, pp. 817-49); and Sebeos 1999, pp. 6-8). A more recent study has argued that there is no reason to doubt the Islamic narrative because Abraha was an ally of Justin II and that his expedition against Makkah was to limit the sphere of influence of the Lakhmīds in Arabia. See (Mishin 2020). Whatever be the case may be, the specific dates do not detract us from the Prophet's birth having been in AD 572/51 BH. 62 (Taqizadeh 1937, p. 129).
Al-Khawārizmī also said: "The first of the month of Muh . arram in that year was a Friday." 63 The date Sunday 13 Muh . arram 51 BH falls as Sunday 14 February AD 572 on the SCC. It was therefore the day when Abraha conducted his expedition against Makkah. The day of the week for 1 Muh . arram 51 BH was either a Monday or a Tuesday, and so al-Khawārizmī's observation that 1 Muh . arram 51 BH fell on a Friday is incorrect. The Prophet's birth would therefore have been approximately two months after the day of the elephant on Monday 12 Rabī' al-Awwal 51 BH/11 April AD 572 according to the SAC.

The Date of the First Revelation
The Prophet is said to have become a prophet on yawm al-bi'tha (the day of the call), and Muslim scholars are generally in agreement that the Prophet was 40 years old when he received his first revelation. 64 If we accept that this was according to the lunar calendar, then the year of the call would have been in 11 BH, with the Prophet's 40th lunar birthday that year having been on Monday 12 Rabī' al-Awwal 11 BH/1 February AD 611 on the SAC. Though Muslim tradition is unanimous that his first revelation came to him during the month Ramad .ā n while he was in Makkah, Shī'a tradition adds that he became a prophet on 27 Rajab 65 which for the year 11 BH returns as Monday 14 June AD 611 on the SAC. Some traditions state that he became a prophet when he was 40 years old but that the revelation of the Qur'ān first came to him when he was 43 years old 66 which would have been on Monday 12 Rabī' al-Awwal 8 BH/31 December AD 613 on the SCC. One tradition on the authority of Qatāda b. Di'āmah (d. 117 AH/AD 735) states that the Qur'ān was revealed for a period of eight years in Makkah which would render his emigration exactly 8 years later in the year zero AH/AD 621. 67 The fact that the Qur'ān makes a reference to the lunar calendar by recounting the Prophet's first revelation in the month of Ramad .ā n indicates that it was observed as a parallel calendar to the Jewish-Arabian calendar which the Quraysh had adopted. The Qur'ān therefore seems to suggest that the Hijrī calendar was a continuation of the Makkan lunar calendar: The month of Ramad .ā n is the month in which the Qur'ān was revealed, a guidance for mankind with clear proofs of guidance and a criterion (al-furqān) [between right and wrong]. So whoever of you has observed the month should fast during it. As for any of you who are sick or on a journey, then you should fast the remaining number of days at a later date in order to complete the prescribed period of fasting. Allāh desires for you ease, not hardship, and He wants you to complete the prescribed period. Therefore glorify Allāh for having guided you so that you may be grateful (Q2:185).
According to al-T . abarī, there is a difference of opinion among scholars whether the first revelation came down to the Prophet on Monday the 17th, 18th or 24th of Ramad .ā n. 68 It is usually accepted that the Prophet received his first revelation 13 years before his emigration to Madīnah. The 18th of Ramad .ā n 13 BH returns as Monday 24 August AD 609 on the SCC but this would mean he would have been 38 lunar years old at the time. The dates Monday 17 Ramad .ā n 11 BH/2 August AD 611 and Monday 24 Ramad .ā n 11 BH/9 August AD 611 on the other hand return accurately on the SAC when he would have been 40 lunar years old. As, according to the Qur'ān, the day of al-furqān was when the first revelation came down to the Prophet and when the Battle of Badr occurred, it does 63 (al-Qurt . ubī 2010, p. 137). 64 (al-T . abarī 1999b, vol. 6, pp. 60-61). 65 (al-Majlisī 1983, vol. 18, p. 189). 66 (al-T . abarī 1999b, vol. 6, pp. 153-66). 67 (al-T . abarī 1999b, vol. 6, p. 156). 68 (al-T . abarī 1999b, vol. 6, pp. 62-63).
Religions 2021, 12, 42 13 of 21 seem as though the 17th of Ramad .ā n is the most likely date for when both of these events took place.

The Prophet's Hijrah
Though a number of different dates have been proposed for the Prophet's emigration from Makkah to Madīnah, al-Wāqidī expresses certainty over the date of Monday 12 Rabī' al-Awwal. As he explains: The Messenger of Allāh-peace and blessings be upon him-arrived in Madīnah on Monday 12 Rabī' al-Awwal. Some say on 2 Rabī' al-Awwal, but the twelfth is what has been confirmed. 69 The problem with the date of 12 Rabī' al-Awwal is that it does not accurately return as a Monday for the year 1 AH, falling instead on a Thursday or a Friday on the SAC and SCC, respectively. Despite this discrepancy having been noted by various scholars, there is one possibility to resolving this problem which has until now been ignored. It is indeed very plausible that the Prophet arrived in Madīnah in year zero, in other words on Monday 12 Rabī' al-Awwal 0 AH/5 October AD 621, 70 meaning that the calendar officially began in the year 1 AH, the year following his arrival. Ibn Sa'd reports how "the Messenger of Allāh-peace and blessings be upon him-went out of the cave [on the Mount of Thawr] on Monday night, four nights having elapsed in the month of Rabī' al-Awwal, and it is said that on Tuesday [he was] in Qudayd." 71 As the 4th of Rabī' al-Awwal 0 AH returns as Sunday 27 September AD 621 on the SCC, there is a gap of one day in the calculation which appears to be an honest mistake. The narrator most likely meant that 4 days had passed in Rabī' al-Awwal, with the 5th of the month having begun after sunset on Sunday, i.e., on Monday night.
The problem of the Prophet's arrival in Madīnah was thoroughly examined by Shamsi, who proposed that a copyist confused its date with his arrival in Qubā'. Shamsi thereby suggested that the Prophet arrived in Qubā' on Monday 8 Rabī' al-Awwal 72 1 AH/20 September AD 622, remained among the Banū 'Amr b. 'Awf for the Monday, Tuesday, Wednesday, and Thursday, and finally, departed from Qubā' to arrive in in Madīnah on Friday 12 Rabī' al-Awwal 1 AH/24 September AD 622. His assertion is however not supported by Ibn Ish .ā q, who meticulously comments that the guide who assisted the Prophet and Abū Bakr "brought them down to the valley of Ri'm; thence to Qubā' to B. 'Amr b. 'Auf on Monday 12th Rabī'u'l-awwal at high noon." 73 A tradition reported by al-Bukhārī states that "When the Prophet arrived in Madīnah, he noticed that some people among the Jews used to uphold the fast of 'Āshūra'. He then said to them: 'We have more right to observe the fast on this day than you'. He then ordered that the Muslims also fast on that day." 74 The fast referred to here could not have been that of 'Āshūra', as it takes place on the 10th of Muh . arram, but rather to that of Yom Kippur which is the Day of Atonement and which takes place on the 10th of the Jewish month of Tishri. Had the Prophet arrived in Qubā' on Monday 8 Rabī' al-Awwal 1 AH/20 September AD 622, then it would have been on 10 Tishri AM 4383, on the day of Yom Kippur. If, however, he arrived on Monday 12 Rabī' al-Awwal 0 AH/5 October AD 621, then this would have been after Yom Kippur, on Monday 14 Tishri AM 4382.
Al-T . abarī makes no mention of a Jewish fast having been observed upon the Prophet's arrival in Qubā', even though "the first person to see him was one of the Jews, who 69 (al-Wāqidī 1966, vol. 1, p. 2). 70 (ibid.). 71 (Ibn Sa'd 1990, vol. 1, p. 179). 72 (al-Bīrūnī 2000. Al-Bīrūnī appears to be the only Muslim writer to record this date, perhaps based on a correction that he made to make the date conform to the fast on Yom Kippur. 73 (Guillaume 2006, p. 227 had observed what we were doing and knew that we were expecting the arrival of the Messenger of Allāh. He shouted out at the top of his voice, 'Banū Qayla, here is your good fortune who has come!'" 75 This may suggest that the Prophet, along with some Arabian Jews, may have considered that Yom Kippur should be observed on the 10th of the month of Muh . arram on the lunar calendar, i.e., on the day of 'Āshūra'. As such, the Prophet could have instituted the practice of fasting on the day of 'Āshūra' in the following year to commemorate the Day of Atonement according to its lunar calculation. The alternative date offered by al-Wāqidī for the Prophet's arrival in Madīnah is that of 2 Rabī' al-Awwal which falls for the year zero as either Thursday 24 or Friday 25 September AD 621, and for the year 1 AH as either Monday 13 or Tuesday 14 September AD 622. Though it is a possibility that the Prophet arrived in Madīnah on 2 Rabī' al-Awwal 1 AH/Monday 13 September AD 622, this date is nevertheless undermined by the possibility of him having departed from the cave on the Mount of Thawr on Monday 5 Rabī' al-Awwal 0 AH/29 September AD 621. 76 Bearing in mind how Qubā' was considered part of Madīnah, lying within its periphery, we see no reason why we cannot accept at face value al-Wāqidī's confirmed report, meaning that the Prophet arrived in Madīnah on Monday 12 Rabī' al-Awwal 0 AH/5 October AD 621.

The Battle of Badr
The Islamic sources have reported six specific dates for the Battle of Badr, all of which seem to describe different episodes in the Muslims' confrontation with the Quraysh, and which all return accurately for the year 1 AH. These range from the specific date the Prophet left Madīnah in preparation for the battle, the date of the battle itself, and the specific date of the Prophet's return. These specific dates have been reproduced below in their chronological order: Ramad .ā n . . . The attack on the people of Badr was on Friday 17 [nights] having passed in the month of Ramad .ā n." 81 Specific date: Friday 17 Ramad .ā n.
Though Ibn H . abīb and Ibn Sa'd seem to disagree on the date when the Prophet departed from Madīnah (though they may have also referred to two different events), the specific dates of Wednesday 8 Ramad .ā n and Saturday 12 Ramad .ā n both return accurately for 1 AH. Although an alternative specific date has been reported claiming that the Battle of Badr took place on Monday 17 Ramad .ā n, this seems to have been a corrective by later scholars to make it fit the calendar for the year 2 AH. The date of Friday 17 Ramad .ā n was so entrenched in the Muslims' consciousness that an early authority, Muh . ammad b. S .ā lih . b. Dīnār al-Tamār (d. 168 AH), was dumbfounded as to how anyone could even express doubt concerning its date. Al-T . abarī records how Ibn Sa'd commented from al-Wāqidī: I mentioned this to Muh . ammad b. S .ā lih . , and he said: "This is the most amazing thing! I never supposed that anyone in the world would doubt this! It was on the morning of 17 Ramad .ā n, on Friday." Muh . ammad b. S .ā lih . said to me (and I heard 'Ās . im b. 'Umar b. Qatāda and Yazīd b. Rumān saying this), "O my nephew, what need have you to name authorities on this subject? This is too obvious for that. Even the women in their houses are not ignorant of this!" 83 An account found in al-Istī'āb also supports the event having taken place on a Friday: Abū 'Umar said: The majority say that the Battle of Badr took place on Friday morning, on the seventeenth of the month of Ramad .ā n, and I have not heard anyone say that it was on a Monday. 84 It is significant that the Battle of Badr is supposed to have taken place on the day of al-furqān, 85 as the Qur'ān attests: And know that anything you obtain of war booty-then for Allāh is one fifth of it, and for the Messenger, his near relatives, the orphans, the needy, and the traveler, if you believe in Allāh and in that which We sent down to Our servant on the day of al-furqān, that is the day when the two armies met. And Allāh, over all things, is able. (Q8:41) The Battle of Badr is said to have occurred one year after the Prophet's emigration, yet it cannot be coincidental for six specific dates to all accurately return for the year 1 AH. It is therefore very plausible that the Hijrah occurred on Monday 12 Rabī' al-Awwal 0 AH/5 October AD 621 and that the Battle of Badr happened one year later on Friday 17 Ramad .ā n 1 AH/25 March AD 623. Finally, it is particularly noteworthy how Nektarios, Patriarch of Jerusalem (d. 1676 CE) records in his Epitomē how the Covenant with the Monks of Mount Sinai was issued after the Battle of Badr, before the end of AD 623. 86
The only specific date for the Prophet's death which returns accurately for the year 11 AH is found in Shī'a sources, that of Monday 28 S . afar 11 AH/25 May AD 632 on the SCC 102 and which coincides with the reported death date of Fāt . ima on Tuesday 3 Jumādā al-Ākhir/25 August AD 632 on the SAC.
If the Prophet died on Monday 28 S . afar 11 AH/25 May AD 632, then his age would have been 60 solar years and 62 lunar years (being 13 days before his 63 rd lunar birthday). If he died on Monday 2 Rabī' al-Awwal 12 AH/17 May AD 633, then he would have been 61 solar years old and 63 lunar years old (being 10 days before his 64th lunar birthday). Had his death been on Monday 12 Rabī' al-Awwal 13 AH/16 May AD 634, then he would have been 62 solar years old, with his death being on the day of his 65th lunar birthday.
The early Muslims may have initially used a calendar that began on yawm al-bi'tha, i.e., on Monday 12 Rabī' al-Awwal 11 BH/1 February AD 611 and which, for a reason that is not clear at this moment in time, ended on Monday 12 Rabī' al-Awwal 2 AH/12 September AD 623 on the SAC. The cycle of 13 years mentioned by the biographers would have thus been completed in 2 AH and the Prophet's stay in Madīnah would have been calculated from that point on, being a period of 10 years, which would support his death in 12 AH. These miscalculations would most likely have been due to the use of competing calendars which may explain some of the discrepancies between the actual specific dates of events and the reported dates as to when they purportedly occurred. As a number of different calendars were used in Arabia at the time of the Prophet, it appears that chroniclers relied on dates emanating from different calendrical systems when making their calculations. Mistakes in the early Muslims' recollection of particular events and erroneous calculations for the year of the Hijrah would certainly have led to these discrepancies.

The Early Issue of the Covenants: A Historical Plausibility?
The early dating of the covenants has been used by critics to completely discredit them. However, it appears that as soon as the Prophet moved to Madīnah, he sought to establish treaties with local tribes through a series of diplomatic initiatives. This was clearly noted by Safwān b. Umayya when he observed: Muh . ammad and his companions have indeed made our trading difficult. We do not know what to do with his companions. They are permanently stationed by the coastline. He [i.e., Muh . ammad] has entered into an agreement with the people of the coast and the majority of them have joined him. 103 If the Islamic state gained recognition after the Battle of Badr as an emerging power, is it then completely far-fetched that communities who believed the Prophet's movement would eventually succeed, and who personally knew him from his days as a merchant, had perhaps requested a covenant of protection from him starting in the year 2 AH? Or could it be that the Prophet, being himself convinced that the religion of Islam would one day spread far and wide, took it upon himself to dispatch these important political documents to the various Christian communities of his time? The Covenant with the Monks of Mount Sinai, which is dated 3 Muh . arram 2 AH/7 July AD 623 on the SCC, 104 is the first covenant to have been issued. The second is the Covenant with the Armenian Christians, which is dated to a Monday in the month of Dhū al-H . ijjah/c.a. May-June AD 624. In light of the specific dates presented in this study, these early dates at the end of the covenants may not be so far-fetched after all.

Conclusions
This study has validated Mahmoud Effendi's conclusions that the pre-Islamic Arabs were in the habit of observing a purely lunar calendar. This study has also argued that the Makkans had adopted a lunisolar calendar that was most likely based on the Jewish calendar. Using the methodology of Specific Date Verification, we have argued that the Prophet's birth was most likely on Monday 12 Rabī' al-Awwal 51 BH/11 April AD 572; his first revelation on Monday 17 Ramad .ā n 11 BH/2 August AD 611; his Hijrah on Monday 12 Rabī' al-Awwal 0 AH/5 October AD 621; the Battle of Badr on Friday 17 Ramad .ā n 1 AH/25 March AD 623; and his death either on Monday 28 S . afar 11 AH/25 May AD 632, Monday 2 Rabī' al-Awwal 12 AH/17 May AD 633, or Monday 12 Rabī' al-Awwal 13 AH/16 May AD 634.
The official Hijrī calendar was instituted the year following his arrival in Madīnah, and it began in 1 AH. This is confirmed by the specific dates found in the Covenant with the Christians of the World and the Covenant with the Jews of Khaybar and Maqnā, as well as the inscription of H . ammat Gader. All other competing calendars which the Arabs were in the habit of observing were, in all likelihood, abrogated by 'Umar b. al-Kat . t .ā b in 17 AH/AD 638. The Prophet's position as head of state in Madīnah was firmly consolidated by the end of 1 AH following the Battle of Badr, after which he forged a number of political alliances with local tribes. It is therefore not so far-fetched that Christian communities who knew and trusted him, and who believed Islam would eventually spread far and wide, requested from him a covenant of protection as early as 2 AH.
Author Contributions: Both authors contributed equally to the writing of this paper in terms of conceptualization, investigation, and development of methodology. Data collection of the specific dates and consultation of French resources was done by Ahmed El-Wakil. Both authors have read and agree to the published version of the manuscript.  one specific date has been recorded for a particular historical event, especially when the data is repeatable and quantifiable, thus rendering the verification of the event being analyzed all the more credible. If we continue our examination of the Farewell Pilgrimage, we find that its historical dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: at al-Wathā Specific Date Verification examines the specific dates recorded for a particular event n the Prophet's life by assuming that the day of the week and month are accurate, but the ear not necessarily so due to miscalculations in the year date. Hamidullah was the first o note that discrepancies in reporting a particular event in different years was not because f a difference of opinion as to whether or not the event occurred in different year dates, ut rather due to differences in calculations. He lists as an example the raid of Banū usṭaliq and notes how Mūsā b. 'Uqbah reported that it occurred in 4 AH; al-Wāqidī in AH; and Ibn Isḥāq in 6 AH. Hamidullah reconciles these three different opinions by ostulating that the early biographers differed in their calculation of the Hijrah: some calulated it in the year of the pledge of 'Aqaba, others in the year of the Prophet's emigraion, and others still in the first year after his emigration. 28 Hamidullah's main premise, as we shall argue, is correct, but he unfortunately never eveloped it as an alternative to his theory of the Hammurabian calendar being the basis f the Quraysh calendar. Hamidullah noticed how the Islamic sources record "not only he date but also the day" 29 of particular events in the Prophet's life, and how the "dates iven in extant concordances do not tally." 30 Hamidullah argued that the reason for this s because the Prophet was using a lunisolar calendar until 10 AH. Ironically enough, Haidullah did not at any point entertain the possibility that the Prophet was using a lunar alendar as soon as he arrived in Madīnah, and that the reason why there may have been iscrepancies in tallying the days of the week is because-as he himself had arguedhere may have been inconsistencies in how the year dates were calculated. As specific dates for events in the Prophet's life have mainly been recorded in three orks, namely al-Wāqidī's (d. 207/823 CE) Kitāb al-Mag̱ hāzī; Ibn Sa'd's (d. 230 AH/845 CE) l-Ṭabaqāt al-Kubrā'; and Muḥammad b. Ḥabīb al-Baghdādī's (d. 245 AH/559 CE) Kitāb aluḥabbar, we will use these to build on Hamidullah's initial observation. The specific verfication of dates will subsequently entail checking the day of the week and month using alendar converters to determine the actual year dates of these events on the official Hijrī alendar.
A good book which has reported an accurate arithmetical record of the week day for he first day of every Hijrī month along with its Julian equivalent until October 1582 CE, fter which it adopts the Gregorian calendar, is Kitāb al-Tawfīqāt al-Ilhāmiyyah by een contested by Mathieu Tillier and Naïm Ventehieghem. One of the dates which they record is . Willards Marriott Library at the University of Utah entitled 'P. Utah 520' which has a specific date wwal 57 AH, and which also bears the expression "snh qaḍāʾ al-muʾminīn." If this expression was a han the Hijrī calendar as Tillier and Ventehieghem propose, then how come the specific date con-Calendar is accurate, returning as Monday 26 January AD 677? If anything, this is evidence that ect. See (Tillier and Ventehieghem 2019, pp. 148-88).
iq al-Siyāsiyyah li-l-one specific date has been recorded for a particular historical event, especially when the data is repeatable and quantifiable, thus rendering the verification of the event being analyzed all the more credible.
If we continue our examination of the Farewell Pilgrimage, we find that its historical dating is validated by a report relayed by al-Wāqidī and later by his secretary Ibn Sa'd, that the Prophet departed from Madīnah "on Saturday, five nights remaining in Dhū al-Qa'dah." 37 When we apply a Hijrī-Julian conversion, we find that Saturday 25 Dhū al-Qa'dah 10 AH returns as Saturday 22 February AD 632 on the SCC. Furthermore, Ibn Kathīr commented that the Prophet arrived in Makkah in the year of the Farewell Pilgrimage "on the morning of the fourth of Dhū al-Ḥijjah. That was a Sunday, when daytime came, at dawn, because the first day of Dhū al-Ḥijjah that year was indisputably a Thursday." 38 Indeed, both Thursday 1 Dhū al-Ḥijjah and Sunday 4 Dhū al-Ḥijjah 10 AH return accurately as Thursday 27 February and Sunday 1 March AD 632, respectively, on the SAC.
We here have four specific dates, albeit on two different calendar converters, which means that the month of Dhū al-Qa'dah in the year 10 AH was 29 days instead of 30 days, a natural irregularity not accounted for in the algorithms. The specific dates therefore confirm that the event of the Farewell Pilgrimage began on Saturday 25 Dhū al-Qa'dah 10 AH/22 February AD 632 when the Prophet left Madīnah; that the first date of the month when the Ḥajj was to take place was Thursday 1 Dhū al-Ḥijjah 10 AH/27 February AD 632; that the Prophet arrived in Makkah on Sunday 4 Dhū al-Ḥijjah 10 AH/1 March AD 632; and that he stood on Mount 'Arafat on Friday 9 Dhū al-Ḥijjah 10 AH/6 March AD 632. All of these specific dates align themselves to the Julian calendar for the year 10 AH, validating the accuracy of the dates reported in the historical works for this particular event.
There are other events in the Prophet's life which have more than one specific date attached to them and which we have recorded in Appendix A Table A1. We will revert to these in the article to identify the precise dates of the Hijrah, the Battle of Badr, and to explain the early dating of the covenants. We will also examine the events reported in the year the Prophet passed away such as his last illness, the expedition he ordered against the Byzantines, and Fāṭima's death to offer different possibilities for the year in which he died.

The Evidence from Archaeology
Evidence that the Hijrī calendar was instituted during the early Caliphate is attested in an inscription found in the restored baths of Ḥammat Gader which lie approximately 7 kilometers east of the southern end of the Sea of Galilee. The inscription, preceded by a cross, reads: