The story of Muhammad's encounter with Bahira is found in the works of the early Muslim historians Ibn Hisham, Ibn Sa'd al-Baghdadi, and Muhammad ibn Jarir al-Tabari, whose versions differ in some details. When Muhammad was either nine or twelve years old, he met Bahira in the town of Bosra in Syria during his travel with a Meccancaravan, accompanying his uncle Abu Talib ibn ‘Abd al-Muttalib. When the caravan was passing by his cell, the monk invited the merchants to a feast. They accepted the invitation, leaving the boy to guard the camel. Bahira, however, insisted that everyone in the caravan should come to him. Then a miraculous occurrence indicated to the monk that Muhammad was to become a prophet. According to one version, those were the stigmata that Bahira found on the young Muhammad; other variants of the story say that it was a miraculous movement of a cloud or an unusual behavior of a branch that kept shadowing Muhammad regardless of the time of the day. The monk revealed his visions of Muhammad's future to the boy's uncle (Abu Talib), warning him to preserve the child from the Jews (in Ibn Sa'd's version) or from the Byzantines (in al-Tabari's version). Both Ibn Sa'd and al-Tabari write that Bahira found the announcement of the coming of Muhammad in the original, unadulterated gospels, which he possessed; the standard Islamic view is that Christians corrupted the gospels, in part by erasing any references to Muhammad.
In the Christian polemics against Islam, Bahira became a heretical monk, whose errant views inspired the Qur'an. The names and religious affiliations of the monk vary in different Christian sources. John of Damascus (d.749), the earliest Christian writer to mention Muhammad, claims that Muhammad "having chanced upon the Old and New Testaments and likewise, it seems, having conversed with an Arian monk, devised his own heresy." For Al-Kindi, who calls him Sergius and writes that he later called himself Nestorius, Bahira was a Nestorian. After the 9th century, Byzantine polemicists refer to him as Baeira or Pakhyras, both being derivatives of the name Bahira, and describe him as an iconoclast. Sometimes Bahira is called a Jacobite or an Arian. Bahira is at the center of the Apocalypse of Bahira, which exists in Syriac and Arabic which makes the case for an origin of the Qur'an from Christian apocrypha. Christian authors maintain that Bahira's works formed the basis of those parts of the Qur'an that conform to the principles of Christianity, while the rest was introduced either by subsequent compilers such as Uthman Ibn Affan or contemporary Jews.
B. Roggema, The Legend of Sergius Baḥīrā. Eastern Christian Apologetics and Apocalyptic in Response to Islam (The History of Christian-Muslim Relations. Texts and Studies 9; 2008) (includes editions, translations and further references).
↑ 2.02.1Watt, W. Montgomery. Muhammad: Prophet and Statesman, p. 1. Oxford University Press, 1964
↑St. John of Damascus's Critique of Islam; from Writings, by St John of Damascus (De Haeresibus, chap. 101), The Fathers of the Church vol. 37 (Washington, DC: Catholic University of America Press, 1958), pp. 153-160.