Isaac ben Jacob Ha-Lavan of Prague
ISAAC BEN JACOB HA-LAVAN OF PRAGUE
ISAAC BEN JACOB HA-LAVAN OF PRAGUE (12th century), tosafist of Bohemia. It has been maintained by some that he was called "ha-Lavan" ("white") because of his white hair and by others that the name is derived from the river Elbe. He was also known as Isaac of Bohemia and Isaac of Regensburg. He was a brother of the well-known traveler *Pethahiah of Regensburg. Isaac lived in Germany and in France, where he studied under *Isaac b. Asher ha-Levi, and under Jacob b. Meir *Tam. He was the author of tosafot to Ketubbot and Yoma which have been published on the basis of various manuscripts – Ketubbot (1954) by P.J. Kohn; Yoma by D. Genachowski (1956) and by P.J. Kohn (1960) in a different reading of the manuscript. *Eliezer b. Joel ha-Levi possessed a collection of Isaac's responsa. He is known also to have compiled various piyyutim. The Sefer ha-Yashar of Jacob Tam, containing sayings of Tam preserved by his pupils, also contains traditions transmitted by Isaac (Urbach, Tosafot, p. 82 n. 27). Isaac is mentioned in the tosafot in the printed editions of the Talmud to Yevamot, Ketubbot and Zevaḥim, as well as in the following works of the posekim: Yiḥusei Tanna'im ve-Amora'im, Arugat ha-Bosem, Roke'aḥ (which includes a responsum by Isaac to *Judah b. Kalonymus b. Moses), the responsa of Isaac Or Zarua, and *Meir b. Baruch of Rothenburg (which quotes a complete responsum by him), Orḥot Ḥayyim, Kol Bo, and others. According to Aptowitzer, Isaac died before 1188 but according to Zunz and Tykocinski, after 1193.
Zunz, Lit Poesie, 313, 489; Zunz, Gesch, index; Gross, Gal Jud, 168, no. 4; S.D. Luzzatto, in: Kerem Ḥemed, 7 (1843), 69; V. Aptowitzer, Mavo le-Sefer Ravyah (1938), 174, 260, 296, 375f.; G. Scholem, in: Tarbiz, 3 (1931/32), 276f.; Tykocinski, in: Germ Jud, 1 (1934), 275f.; and index s.v.; Urbach, Tosafot, index s.v.; D. Ganchowsky, in: Sinai, 38 (1956), 288–311; idem (ed.), Tosefot R. Yiẓḥak ben Ya'akov ha-Lavan le-Massekhet Yoma (1956), introduction.
[Shlomoh Zalman Havlin]