Doctrina Jacobi

The Doctrina Jacobi is a Greek Christian polemical tract set in Carthage and written in Syria Palaestina. The composition of the document is generally dated to 634 or shortly afterwards.

It supposedly records a weeks-long discussion ending on July 13, 634, among Jews who have been forcibly baptized by order of the emperor. One of them, Jacob, has come to believe sincerely in Christianity; he instructs the rest about why they should also sincerely embrace their new faith. Halfway through, a Jewish merchant named Justus arrives and challenges Jacob to a debate. In the end, all of the participants are convinced to embrace Christianity, and Jacob and Justus return east. In addition to several partial Greek manuscripts, the text survives in Latin, Arabic, Ethiopic and Slavonic translations.

The text provides one of the earliest external accounts of Islam, presenting a significantly different Islamic historiography than found in traditional Islamic texts. It also shows Jacob comparing the Byzantine Empire to the fourth beast of the prophecy of Daniel from Judeo-Christian eschatology. Although not unfamiliar imagery, it is part of a series of Byzantine literature, from the early stages of the Islamic religion, of trying to reconcile Islam with the apocalyptic vision. Further examples of this are contained in the pseudo-Athanasian's Quaestiones ad Antiochum ducem, and the Quaestiones et responsiones attributed to Anastasius of Sinai.

It records a prophet in Arabia who was waging war. According to Crone, who has presented a highly disputed account of the period, the document contradicts the notion in Islamic tradition that the prophet Muhammad was dead at the time of the conquest of Palestine but agrees with some traditions of other peoples of the time.

• "What is significant here is the possibility that Jews and Arabs (Saracens) seem to be allied together during the time of the conquest of Palestine and even for a short time after"
• "To be sure, the picture given in the Doctrina Iacobi seems garbled, and many of its details disagree with the traditional account (for example, in seeming to describe the prophet as leading the armies of the Saracens himself). ... Yet one could hardly expect a Byzantine source from this early and turbulent period to get all the details right. Even later, most Byzantine sources displayed gross misunderstanding of matters Islamic, just as Muslim sources generally did of matters Byzantine." – Colin Wells.

• English translation by Andrew S. Jacobs