This paper sets out to confirm (it is hoped decisively) the identity of the Jewish philosopher Abraham Ibn Daud with the Arabic-into-Latin translator known as “Avendauth.” Two new arguments are advanced. (1) A short passage in Ibn Daud’s The Exalted Faith unmistakably attests to the author’s acquaintance with the arcane Arabic literature on the branch of mathematics known as muʿāmalāt. It is suggested that Ibn Daud came across this philosophically low-status material at the Toledo Cathedral, where Gundissalinus was leading an Arabic-into-Latin translation team whose projects included the Liber Mahameleth, which draws on precisely these out-of-the-way muʿāmalāt materials. The author of The Exalted Faith could have accessed muʿāmalāt only through Gundissalinus’s circle, with which he must thus have been in contact. (2) Recent studies on Gundissalinus and his circle have shown that the Latins’ Avendauth was an independent thinker of a considerable stature. Given that such a scholar is unlikely to have gone unmentioned in Jewish records, it is suggested that he is Abraham Ibn Daud.