Charles Ellicott Commentary Exodus 29:2

"and unleavened bread, and cakes unleavened mingled with oil, and wafers unleavened anointed with oil: of fine wheaten flour shalt thou make them." — Exodus 29:2 (ASV)

Unleavened bread. —Unleavened bread seems to have been required as purer than leavened, since fermentation was viewed as a type of corruption.

Cakes ... tempered with oil. —Rather, cakes that have had oil poured over them. A moderately thick cake is intended.

Wafers. —These were cakes, or biscuits, extremely thin and unsubstantial, as is implied by the etymology of the term used. Oil is commonly eaten with cakes of both kinds by Eastern peoples.