Sahl ibn Bishr al-Israili (c. 786–c. 845), also known as Rabban al-Tabari and Haya al-Yahudi ("the Jew"), was a Jewish[1][2][3] or Syriac Christian[4][5] astrologer,[6] astronomer and mathematician from Tabaristan. He was the father of Ali ibn Sahl the scientist and physician, who became a convert to Islam.[7]
He served as astrologer to the governor of Khuristan and then to the vizier of Baghdad. He wrote books on astronomy, astrology, and arithmetic, all in Arabic.[8]
Ali ibn Sahl Rabban al-Tabari, the son of a Syriac Christian scholar living in Persia on the Caspian Sea...
Ibn al-Qiftî (4) renders the title Rabban correctly but with a false explanation, taking it for the Jewish title of Rabbi. So 'Alî b. Rabban passed into all historical works, until quite recently, as a Muslim of Jewish origin, although 'Alî himself, in the preface to his work, explains this title Rabban as being the Syriac word for "our Master" or "our Teacher". The late Professor Horovitz told me and wrote to me several years ago, that this was a Christian title; A. Mingana gave the proof of this in print for the first time in I922. 'Alî says in his apologetic tract "The Book of Religion and Empire", which he wrote about 855 A.D., that he himself was a Christian before he was converted to Islam, and that his uncle Zakkâr was a prominent Christian scholar.