Moses took some of the anointing oil and some of the blood that was on the altar, sprinkled it on Aaron and his clothes and on his sons and their clothes. In this way he dedicated Aaron, his clothes, his sons, and their clothes.
Nadab and Abihu died in the Lord’s presence because they offered unauthorized fire in his presence in the Desert of Sinai. They had no children. So only Eleazar and Ithamar served as priests during the lifetime of their father Aaron.
Moses’ Teachings designated mortals as chief priests even though they had weaknesses. But God’s promise, which came after Moses’ Teachings, designated the Son who forever accomplished everything that God required.