Sahl (Abū ʾl-Sarrī) ben Maṣliaḥ was a Karaite exegete, legal scholar and propagandist who lived in the second half of the tenth century. The overwhelming majority of his works, composed both in Hebrew and in Arabic—sometimes with the two languages combined in the same composition—remain in manuscript and await publication. Sahl, the Arabic rendering of the Hebrew name Jashar, was a resident of Jerusalem, but according to his own testimony traveled abroad as a missionary seeking to convert Rabbanites to Karaism. He is best known for his anti-Rabbanite polemic in Hebrew known as SeferTokh…