Leviticus 4:34-35

34Then the priest shall take some of the blood of the sin offering with his finger and put it on the horns of the altar of burnt offering and pour out the rest of the blood at the base of the altar. 35They shall remove all the fat, just as the fat is removed from the lamb of the fellowship offering, and the priest shall burn it on the altar on top of the food offerings presented to the LORD . In this way the priest will make atonement for them for the sin they have committed, and they will be forgiven.