Third exilarch of the Arabian period; died in 730. He was a descendant of Bostanai I. and a successor of ?anina b. Adai. His eldest son was Solomon b. ?asdai, who also, after his father's death, became exilarch. His second son, David, was the father of Anan ben David, the founder of the Karaites, and, according to Karaite tradition, was gaon. ?asdai's son-in-law, probably, was Na?ronai ben Nehemiah, gaon of Pumbedita (719-739). ?asdai I. is certainly the exilarch quoted in Al-?azwini's "Athar al-Bilad" (ed. W�stenfeld, p.203), though his name is not mentioned. According to this report he showed to Mujahid (724) the two angels Harut and Marut, great teachers of magic (see Hughes, "Dict. of Islam," p. 167). It is related that Mujahid, against ?asdai's express condition, pronounced the name of God on seeing them, and thus did not perish.