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. He shall put some of the blood on the horns of the altar which is before the LORD in the tent of meeting; and all the blood he shall pour out at the base of the altar of burnt offering which is at the doorway of the tent of meeting.

Then the priest is to 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 the rest of its blood he shall pour out at the base of the altar of burnt offering.