Jacob ben-Eleazar a Jewish grammarian, flourished at Toledo in the first half of the 12th century. He distinguished himself by a work entitled הִשָּׁלֹם סֵפֶי (the book of completion), which investigates the nature of the vowel-points of Hebrew, and also the etymology of proper Hebrew names; it was freely used by Kimchi, as is proved by frequent citations. "Jacob ben-Eleazar was a sound grammarian, laid down some excellent rule respecting the Hebrew syntax, and materially aided the development of philology in Spain at a time when Biblical exegesis was much neglected and the study of the Talmud was paramount" (Dr. Ginsburg, in Kitto, s.v.). He was also active in the correction of the Hebrew text of the O.T., and for this purpose relied on the celebrated Codex Hillali or Helali, one of the most ancient and celebrated Hebrew codices. It was written, according to some, at Hilla, a town built near the ruins of the ancient Babel, and hence the name by which the MS. 'is designated; others, however, hold that it was the production of Rabbi Moses ben-Hillel. It bears date from the beginning of the 7th century, according to Sakkuto, who in his day (circa 1500) saw a portion of the Codex, and pronounced it to be 900 years old, and cites Kimchi (Juchassin, ed. Filipowski, Lond. 1857, p. 220) as saying in his grammar on Nu 15:4, that the Pentateuch of this Codex was in his day extant at Toledo. The probability is that a greater portion of it, if not the whole, was destroyed at Leon, in Spain, where it was last deposited, during the persecutions of the Jews and the destruction of all Jewish writings in 1197. Jacob ben-Eleazar's correction of the text of the O. — T. Scriptures by the aid of this celebrated Codex makes it, therefore, doubly valuable for all critical students of the Hebrew text. See Biesenthal and Lebrecht's Radicumn Liber (Berlin, 1817), p. 15, 26; Geiger, in Ozar Nechmad II (Vienna, 1857), p. 159 sq.; Grätz, Gesch. d. Juden, 6, 132; Kitto, s.v. SEE MANUSCRIPTS, BIBLICAL.