The Siddur (prayerbook) of Saadia Gaon is the earliest surviving attempt to transcribe the weekly ritual of Jewish prayers for week-days, Sabbaths, and festivals (apart from the prayer book of Amram Gaon, of which there is no authoritative text). The text also contains liturgical poetry by Saadia, as well as Arabic language commentary. There is no known extant manuscript of the entire text, though there is a near complete manuscript in Oxford. Fragments have also been found in the Cairo Genizah. The prayerbook apparently served as a basis for later efforts to codify the Jewish prayer ritual and set it down in writing and was imitated by later authors.
An edition based on these manuscripts has been published by Davidson, Assaf and Yoel in Jerusalem in 1941. The Arabic portions are accompanied by translations into Hebrew in facing columns.