The unleavened bread was to show that the priests should be, and that Christ really was, free from all malice and hypocrisy, both which are compared to leaven, Luke 12:1 1 Corinthians 5:8, and that all the services offered to God by the priests were to be pure and unmixed.
Related Commentaries of Exodus 29:2
Exodus 29:2
2 And unleavened bread, and cakes unleavened tempered with oil, and wafers unleavened anointed with oil: of wheaten flour shalt thou make them.