Сефер Йецира
In his commentary on the "Sefer Yetzirah", Saadia sought to render lucid and intelligible the content of this esoteric work by the light of philosophy and scientific knowledge, especially by a system of Hebrew phonology which he himself had founded. He did not permit himself in this commentary to be influenced by the theological speculations of the Kalam, which are so important in his main works. In introducing "Sefer Yetzirah"'s theory of creation he makes a distinction between the Biblical account of creation ex nihilo, in which no process of creation is described, and the process described in "Sefer Yetzirah" (matter formed by speech). The cosmogony of "Sefer Yetzirah" is even omitted from the discussion of creation in his magnum opus "Kitab al-Amanat wal-I'tiḳadat." Concerning the supposed attribution of the book to the patriarch Abraham, he allows that the ideas it contains might be ancient. Nonetheless, he clearly considered the work worthy of deep study and echoes of "Sefer Yetzirah"'s cosmogony do appear in "Kitab al-Amanat wal-I'tiḳadat" when Saadia discusses his theory of prophecy.