Levi ben Japheth (Heb. Levi ben Yafet ha-Levi; Arab. Abu Sa'id Levi ibn Yafat was a Karaite Jewish scholar who flourished, probably at Jerusalem, in the first half of the eleventh century CE.
Although, like his father Japheth ben Ali, he was considered one of the greatest authorities among the Karaites, who called him "al-Shaikh" (the master), no details of his life are to be found in the Karaite sources. There even exists confusion in regard to his identity; in some of the sources he is confounded with his brother, or his son Sa'id (comp. Pinsker, "Liqqute Qadmoniyyot," p. 119), and also with a Muslim scholar named Abu Hashim (Aaron ben Joseph, "Mibhar," Paris MS.). Levi wrote in Arabic a comprehensive work on the precepts, parts of a Hebrew translation ("Sefer ha-Mitzvot") of which are still extant in manuscript (Neubauer, Cat. Bodl. Hebr. MSS. No. 857; Steinschneider, Cat. Leyden, No. 22; St. Petersburg MSS., Firkovich collection, No. 613). This work, which was used by nearly all the later Karaite codifiers, contains valuable information concerning the differences between the Karaites and the Rabbinites (in whose literature the author was well versed), and the dissensions among the Karaites themselves. Thus in the section dealing with the calendar, in which the year 1007 is mentioned, Levi states that in Iraq the Karaites in their determination of Rosh ha-Shannah, resembled the Rabbinites in so far as, like them, they took for their basis the autumnal equinox, while in some places the Karaites adopted the Rabbinite calendar completely.
Levi distinguishes between the views, in regard to the calendar, of the earlier and the later Rabbinites, and counts Saadia, whom he frequently attacks with the utmost violence, among the latter. In the treatise on tzitzit Levi says that he drew his material from the works of his father and of his predecessors. He excuses the inadequacy of treatment marking some parts of the work on the ground of the lack of sources and of the various trials and sicknesses he had suffered during its composition.
Levi's "Muqaddimah," an introduction to the pericopes of the Pentateuch, is no longer in existence. A fragment, on Deut. i., of the Hebrew translation of Moses ben Isaiah Firuz was in the Firkovich collection and was published by Pinsker, but was lost during the Crimean war. He wrote also a short commentary on the Earlier Prophets, a fragment of which, covering the first ten chapters of Joshua, still exists (Brit. Mus. Or. No. 308). Steinschneider believes it possible that Levi was also the author of the short commentary on Psalms found in the British Museum (No. 336). According to Ali ben Sulaiman, Levi made a compendium of the lexicon "Agron" of David ben Abraham; however, this is contested by Abu al-Faraj, who asserts that the compendium was prepared by David himself.
This article incorporates text from a publication now in the public domain: Jewish Encyclopedia. 1901–1906.