David (Dāwūd) ibn Marwān al-Muqammiṣ (perhaps al-Muqammaṣ) was active in mid-ninth-century Syria and northern Iraq, and was the first medieval Jewish philosopher to leave identifiable writings. He is said to have converted to Christianity, studied many years with Nonnus of Nisibis, and then returned to Judaism; his writings demonstrate a great deal of Christian influence. Both Karaites and Rabbanites claim him as one of their own, but the evidence is not sufficient to make a definite identification. Very little is otherwise known about him.

Al-Muqammiṣ wrote Arabic treatises on…