Leviticus 9:8-9, 18

Aaron therefore went unto the altar, and slew the calf of the sin offering, which was for himself. And the sons of Aaron brought the blood unto him: and he dipped his finger in the blood, and put it upon the horns of the altar, and poured out the blood at the bottom of the altar

He slew also the bullock and the ram for a sacrifice of peace offerings, which was for the people: and Aaron's sons presented unto him the blood, which he sprinkled upon the altar round about