Aaron Ha-Rishon (i.e. the elder), a celebrated rabbi of the sect of the Caraites, practiced medicine at Constantinople toward the close of the 13th century. He had the reputation of being a great philosopher and an honest man. He is the author of an Essay on Hebrew Grammar (כּלַיל יֹפַּי, "perfect in beauty," Constantinople, 1561), and of a Jewish prayer-book according to the rites of the Caraitic sect (סֵפֶר תּפַּלּוֹת, Venice, 1528-29, 2 vols. 4to). He also wrote commentaries on the Pentateuch, the first prophets (Joshua, the Judges, Samuel, and the Kings), on Isaiah and the Psalms, and on Job, all of which are still inedited. — Hoefer, Biographie Generale, 1, 6.