Tosafist; lived at Speyer in the eleventh century; son-in-law of Eliakim ben Meshullam and pupil of Rashi. His are the earliest known tosafot, and are mentioned, under the name of "Tosafot Riba," in the "Temim De'im," in the printed tosafot (Soṭah 17b), and in the "Tosafot Yeshanin" (Yoma 15a). They are frequently quoted without the name of their author. Isaac ben Asher also wrote a commentary on the Pentateuch, which is no longer in existence. It is cited in the "Minḥat Yehudah," and Jacob Tam made use of it in his "Sefer ha- Yashar" (p. 282).

Bibliography: Azulail, Shem ha-Gedolim;
Zunz, Z. G. p. 31;
Michael, Or ha-Ḥayyim, p. 501, No. 1074.S. S. I. Br.