Leviticus 4:17-18, 25

and the priest shall dip his finger in some of the blood, and sprinkle it seven times before the LORD, even before the vail. And he shall put some of the blood upon the horns of the altar which is before the LORD, that is in the tabernacle of the congregation, and shall pour out all the blood at the bottom of the altar of the burnt offering, which is at the door of the tabernacle of the congregation.

And the priest shall take of the blood of the sin offering with his finger, and put it upon the horns of the altar of burnt offering, and shall pour out his blood at the bottom of the altar of burnt offering.