REUBEN BEN ḤAYYIM (d. before 1276), Provencal talmudist. Reuben studied under Isaac ha-Kohen, a disciple of *Abraham b. David of Posquieres. Few biographical details are known of him. Both he and his brother Abraham composed piyyutim. Among his prominent pupils were *Manoah of Narbonne and Menahem b. Solomon *Meiri. The latter praises his teacher at great length both on account of his comprehensive knowledge of the Talmud and his general culture (Introd. to Beit ha-Beḥirah to Avot ed. by B.Z. Prag (1964), 56). Reuben was the author of Sefer ha-Tamid, a philosophical commentary on the liturgy, which seems also to have contained laws concerning the prayers together with a commentary.
A fragment of the commentary was published in the collection Oẓar ha-Ḥayyim, 11 (1935). *Aaron b. Jacob ha-Kohen of Lunel utilized the work in his Orḥot Ḥayyim and it is evident that *Abudarham also used it. But apart from these it was not widely used nor were copies of it available. It was used as late as the 18th century by Judah b. Meir Toledano, a Moroccan scholar. Azariah dei Rossi (Me'or Einayim, section "Yemei Olam," ch. 40) mentions a commentary on the aggadot of the Talmud by Reuben. According to Geiger, *Levi b. Abraham b. Ḥayyim was a nephew of Reuben.
A. Geiger, Kevuẓat Ma'amarim, ed. by S. Poznański (1910), 254–85; J.M. Toledano, in: Oḥar ha-Ḥayyim, 11 (1935), 1–42; idem, Oẓar Genazim (1960), 207f.; S. Hurvitz, in: Talpioth, 9 (1964), 146–9; S.K. Mirsky (ed.), Ḥibbur ha-Teshuvah le-R. Menaḥem b. Shelomo ha-Me'iri (1950), 13–16 (introd.).