Leviticus 9:7-9

New King James Version

⁷ And Moses said to Aaron, “Go to the altar, ^(A)offer your sin offering and your burnt offering, and make atonement for yourself and for the people. ^(B)Offer the offering of the people, and make atonement for them, as the Lord commanded.”

⁸ Aaron therefore went to the altar and killed the calf of the sin offering, which was for himself. ⁹ Then the sons of Aaron brought the blood to him. And he dipped his finger in the blood, put it on the horns of the altar, and poured the blood at the base of the altar.