A famous physician in Cairo, Samuel (Abū Manṣūr) ben Hananiah came from a family of physicians that included his father and brother and was appointed court physician to the Fatimid caliph al-Ḥāfiẓ (r. 1131–1149). According to Muslim chroniclers, his master, facing the prospect of a civil war between his two sons, summoned Samuel immediately upon his ascent to the throne along with another physician, a Christian. He asked Samuel to prepare a deadly drug for one of the sons. Samuel refused, claiming he did not know how to prepa…