Charles Spurgeon Commentary Leviticus 16:5-6

"And he shall take of the congregation of the children of Israel two he-goats for a sin-offering, and one ram for a burnt-offering. And Aaron shall present the bullock of the sin-offering, which is for himself, and make atonement for himself, and for his house." — Leviticus 16:5-6 (ASV)

These priests were sinful, and therefore they must first themselves be purged from guilt before they could come near to God; but the true High Priest of God, our Lord Jesus, needed to offer no sacrifice for himself, for he was pure and without blemish or stain of sin.