Thirteenth-century physician, priest, and author. The most significant, modern source of information on him is G. Graf’s Geschichte der christlichen arabischen Literatur (1947, Vol. 2, pp. 344-48), from which the following data come.

His writings, largely in defence of Christianity, were composed in the period between 1204 and about 1245 at the latest. Among these is al-‘Uqul fi ‘ al’Usul (Theriac of the Understanding in the Science of the Fundamentals), a work he wrote at the instigation of the vizier Taqi al-Din. It was to serve as an “antidote” to Muslim polemicists. The twenty-four chapters of the principal dogmatic section discuss Christian teachings on the Trinity and Incarnation; the theology of the religions preceding Christianity, that is, the heathenism of “the philosophers,” Zoroastrian dualism, and polytheism; the general resurrection, the reverence of images, baptism, and the Eucharist. A second part explains and justifies the Christian moral code. In the appended compendium of abstracts, the Jewish philosopher Maimonides (d. 1204) and the Muslim philosopher al-Razi (d. 1209) are cited among non-Christian writers. Al-Mu‘taman Abu Ishaq ibn al-‘Assal took an excerpt from the for his Majmu‘ Usul al-Din (Compendium of the Principles of Religion) and introduced it with these words: “There is a treatise by the esteemed priest, the wise, respected, learned, and energetic administrator [al-‘Alim wa-al-‘Amil] al- Abu al-Khayr, the physician who assisted in the composition of this book—God keep him long among the living and preserve also that which results from his actions and teachings—from which I have taken the following.”

The of the Beliefs and a treatise are found in Vatican manuscripts adjoined to the Tiryaq where they are attributed to IBN KABAR. They are, however, from the pen of Ibn al-Tayyib. The Summa [or the Most Important] of the beliefs of the Christian Faith and Refutation of the Islamic and Jewish Peoples from Their Own Principles and Fundamentals was also written at the request of Muslim and Jewish friends. In it Ibn al-Tayyib explains the doctrine of the Trinity (in the preface) and demonstrates the of Christ (in three chapters). The quotations from church fathers (Didascalia, Irenaeus, Dionysius, Chrysostom) are taken from the anthology, Confessions of the Fathers. In a treatise Ibn al-Tayyib refutes fatalism and the erroneous doctrine of the temporality and the creation of the nature of Christ. He relies even more heavily on Confessions of the Fathers for quotations than he did in the .

In the Fihris (Compendium) of Sbath are listed 131 sermons by Ibn al-Tayyib titled Sermons for Sundays and Holidays, and ibn Kabar cites “Sermons” among the written works of Ibn al-Tayyib. It is possible that the sermons mentioned by Ibn Kabar are to be identified with those listed in the Fihris. It is also possible that the sermons discussed in Sbath are to be found in the collection of eighty-seven sermons based on on the Gospels by John Chrysostom that Abu al-Khayr arranged and assigned to specific days of the Coptic calendar (see Graf, Vol. 1, pp. 340-41).


  • Al-Mu’taman Abu Ibrahim ibn al-‘Assal. Majmu‘ Usul al- Din. Cairo, 1908.
  • Sbath, P. Al-Fihris (Catalogue de manuscrits arabes). 3 vols in 2. Cairo, 1938-1940.