Kohen Ṣedeq Bar Ivomay (or Ikhomay) Gaon was head of the Sura yeshiva in Iraq from 838 to 848 (alternatively, 832 to 843). From the few sources attributable to him with a measure of confidence, it appears that Kohen Ṣedeq was one of the Babylonian authorities consulted on legal matters by the heads of the Jewish community of Qayrawan. A ruling of his on a liturgical question is also cited by the Andalusian scholar Isaac ben Judah ibn Ghiyyāth, and the reference therein to “the seder of Rav Kohen Ṣedeq” has led to the suggestion that he was one of the first to compile a prayerbook. Another of his respon…