Jewish astrologer and mathematician who, like Masha’allah, moved from Persia to work as a court astrologer at Baghdad. He was the first to translate Ptolemy’s Almagest into Arabic and is famous for composing a set of five treatises, which offer a comprehensive study of astrology under the headings: I: Introduction, II: Fifty Judgements, III: On Questions, IV: On Elections, V: On Time. The treatise On Questions was especially important in the transmission of horary technique. Sahl was heavily influenced by Dorotheus and Masha’allah, and in turn his work was influential upon Guido Bonatti and William Lilly.  Ben Dykes published English translations of several texts by Masha’allah and Sahl in his Works of Sahl & Masha’allah (Cazimi Press, 2008).