ISAAC IBN JASOS IBN SAḲṬAR (more correctly Abu Ibrahim Isaac ibn Yashush ; also called Yiẓḥaḳi):
Spanish grammarian; born 982; died at Toledo about 1057-58. He is identified by Steinschneider with the physician Isḥaḳ ibn Ḳasṭar or, as Moses ibn Ezra calls him, Isḥaḳ ibn Saḳṭar ("Z. D. M. G." viii. 551, ix. 838). According to Ibn Abi Uṣaibi'a ("'Uyun al-Anba'," ii. 50), he was the physician in ordinary of Muwaffaḳ Mujahid al-'Amiri and of his son Iḳbal al-Daulah, kings of Denia. He was well trained in logic, Hebrew grammar, and Jewish law, and was conversant with the opinions of the philosophers. Moses ibn Ezra (l.c.) called him and Abu al-Walid the two sheiks of Hebrew grammar.
He wrote in Arabic "Sefer ha-Ẓerufim" (the Arabic title of which was, probably, "Kitab al- Taṣarif"; Neubauer, in "Journal Asiatique," 1862, ii. 249), on inflection. It is known only from references to it by Abraham ibn Ezra, who, in his commentary on the Bible, often condemns Isaac's exegesis because of its too bold historical criticism. Thus, Isaac ibn Jasos holds that Gen. xxxvi., in which the genealogy of the kings of Edom is given, was not written earlier than the time of King Jehoshaphat. He also identified the "Hadad" of Gen. xxxvi. 35 with "Hadad the Edomite" of I Kings xi. 14; the "Mehetabel" of Gen. xxxvi. 39 with the "sister of Tahpenes" of I Kings xi. 19; Jobab ben Zerah with Job; the prophet Hosea ben Beeri with Hosea ben Elah, the last king of Israel (see Ibn Ezra on Hosea i. 1, and comp. Isa. xv. 8, where both seem to be mentioned in the word "Beer-elim").
Such opinions, seemingly drawn from Moses ibn Gikatilla, caused Ibn Ezra to declare that Isaac ibn Jasos' book deserved to be burned as the work of a "prattler ["mahbil"] of vain things" (see Ibn Ezra on Job xlii. 16 and Gen. xxxvi. 32). Isaac may likewise be the "mahbil" whom Ibn Ezra opposes because he desired to alter words or expressions in more than 200 passages in the Bible ("Safah Berurah," ed. Lippmann, p. 9b, Fürth, 1839; "Ẓaḥḥut," ed. Lippmann, p. 72a, ib. 1834). This system of substitution had been used for the first time by Abu al-Walid.
- Carmoly, in Zion, i. 46;
- Neubauer, in Journal Asiatique, 1862, ii. 257;
- Steinschneider, Die Arabische Litteratur der Juden, p. 135;
- compare also Wolf, Bibl. Hebr. i. 662;
- Geiger, Wissenschaftliche Zeitschrift, i. 20;
- Grätz, Gesch. vi. 42.;
- Winter and Wünsche, Die Jüdische Litteratur, ii. 183, 262, 335;
- Poznanski, Mose ibn Chiqitalla, pp. 54, 136, Leipsic, 1895.