Karaite rabbi at Koslov, now Eupatoria, Crimea, in the first half of the nineteenth century. His father, Joseph Solomon, whom he succeeded in the rabbinate, instructed him in the literature and science of the Karaites. He is the author of six Hebrew poems, which are found in the "Karaite Liturgy" (Vienna ed., pp. 168 et seq.). In a poem, composed in honor of Simḥa Bobowich, who was head of the Koslov community—which poem is also incorporated in the "Liturgy" (p. 187)—he calls himself, from the initials of his father's name, Ibn Yashar.