This book contains a critical edition, an English translation, and a detailed commentary of two lengthy Hebrew liturgical poems for the Day of Atonement (called Seder Avodah) that were composed by a ninth- or tenth-century Jewish poet who apparently lived in Palestine or its environs, Shelomoh Suleiman Al-Sinjari. The first part of the Seder Avodah narrates the creation of the world and the history of the people of Israel from the perspective of the sins that they have committed, while its second part describes, in detail, the ritual service of a high priest (Aaron and his sons) in the temple on the Day of Atonement.