Leviticus 9:7-9

New Catholic Bible

⁷ Moses said to Aaron, “Come to the altar. Offer your sin offering and your burnt offering and make atonement for yourself and for your people. Present the people’s offering and make atonement for them, as the Lord has commanded.”

⁸ Aaron therefore drew near the altar and slew the calf of the sin offering, the offering for himself. ⁹ His sons brought the blood to him and he dipped his finger in it and put it on the horns of the altar, pouring the rest of the blood out at the base of the altar.