Leviticus 9:7-10

Then Moses said to Aaron, “Draw near to the altar and offer your sin offering and your burnt offering and make atonement for yourself and for the people, and bring the offering of the people and make atonement for them, as the LORD has commanded.” So Aaron drew near to the altar and killed the calf of the sin offering, which was for himself. And the sons of Aaron presented the blood to him, and he dipped his finger in the blood and put it on the horns of the altar and poured out the blood at the base of the altar. But the fat and the kidneys and the long lobe of the liver from the sin offering he burned on the altar, as the LORD commanded Moses.