Leviticus 4:17-18, 25

and the priest shall dip his finger in the blood and sprinkle it seven times before the LORD in front of the veil. And he shall put some of the blood on the horns of the altar that is in the tent of meeting before the LORD, and the rest of the blood he shall pour out at the base of the altar of burnt offering that is at the entrance of the tent of meeting.

Then 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 its blood at the base of the altar of burnt offering.