Commentary Purg VIII 10-12

The praying figure is facing east, not because the sun is there (it is setting in the west), but because the east is traditionally associated with Christ as 'rising sun.'  For the Virgilian provenance of his gesture see Tommaseo (DDP Tommaseo.Purg.VIII.10-12): Dante's 'levò ambo le palme' is indeed close to Virgil's (Aen. X.844-845): 'et ambas / ad caelum tendit palmas.'  However, Heilbronn (Heil.1972.1), pp. 56-57, points out that his action 'imitates the words of Psalm 133:3: "In noctibus extollite manus vestras in sancta, et benedicite dominum" [134:1-2: by night... lift up your hands in the sanctuary and bless the Lord].  At Compline, this psalm immediately precedes the hymn, Te lucis, as the gesture does in Purg. VIII.'