Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. David (abu Sulaiman) ibn Merwan al-Mukkamas al-Rakki (died c. 937) was a philosopher and controversialist, the author of the earliest known Jewish philosophical work of the Middle Ages. He was a native of Rakka, Mesopotamia, whence his surname. Harkavy derives his byname from the Arabic " amma " (to leap), interpreting it as referring to his asserted change of faith (Grätz, Gesch. Hebr. transl., iii.498). This is uncertain. The name is written " " in Masudi''s Al-Tanbih (ed. De Goeje, p. 113), in a Karaitic commentary to Leviticus, and in a manuscript copy of Jefeth''s commentary to the same book (Jew. Quart. Rev. viii.681), and is perhaps a derivative from the city of umis in Taberistan (Ya ut, iv.203). Another Karaite bears the name "Daniel al- umisi," and in Al- Hiti''s chronicle this name is also spelled with a ade (Jew. Quart. Rev. ix.432).