Leviticus 8:14-15

14He then presented the bull for the sin offering, and Aaron and his sons laid their hands on its head. 15Moses slaughtered the bull and took some of the blood, and with his finger he put it on all the horns of the altar to purify the altar. He poured out the rest of the blood at the base of the altar. So he consecrated it to make atonement for it.