John Calvin on Leviticus 9:7-21

7. And Moses said unto Aaron, Go unto the altar Here is repeated what was stated elsewhere, that the priest, as being himself a sinner, must first make entreaty for himself, before he propitiates God towards others. Hence the Apostle justly infers that the legal priesthood was weak and merely typical. (Hebrews 5:1.) For none can be a true peace-maker, except he, who, in reliance on his perfect innocence, presents himself before God to obtain pardon for others, and, being pure from every blemish, requires no expiation for himself. All else to the end of the chapter I pass over, because Moses only records how Aaron sacrificed according to God’s command and the legal ritual.