Charles Ellicott Commentary Leviticus 9:7

"And Moses said unto Aaron, Draw near unto the altar, and offer thy sin-offering, and thy burnt-offering, and make atonement for thyself, and for the people; and offer the oblation of the people, and make atonement for them; as Jehovah commanded." — Leviticus 9:7 (ASV)

And Moses said to Aaron. —Though he was now the duly-installed high priest, yet he did not approach the altar until he was solemnly called upon by Moses to do it, thereby showing the authorized representatives of the people that Aaron did not take this honor to himself, but that it was the call of God by Moses. Hence, the remark of the Apostle, And no man taketh this honour unto himself, but he that is called of God, as was Aaron; so also Christ glorified not himself to be made an high priest, but he that said unto him, etc. (Hebrews 5:4–5).

Make atonement for yourself and the people. —The fact that these sacrifices which the high priest is to bring are here described as designed to make atonement for himself and the people, goes far to confirm the ancient interpretation that reference is here made to the particular sin which Aaron and the people committed in common, and that it is the sin of the golden calf , which is so emphatically described in the words they made the calf which Aaron made (Exodus 32:35). Hence, while their share of the sin is to be atoned by a special sacrifice , they are yet to participate in the atoning virtue of Aaron’s sacrifice because they prevailed on him to make the calf (Exodus 32:1).