Leviticus 4:17-18

4:17 and that priest must dip his finger in the blood and sprinkle some of the blood seven times before the Lord toward the front of the veil-canopy. 4:18 He must put some of the blood on the horns of the altar which is before the Lord in the Meeting Tent, and all the rest of the blood he must pour out at the base of the altar of burnt offering that is at the entrance of the Meeting Tent.

Leviticus 4:25

4:25 Then the priest must 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 he must pour out the rest of its blood at the base of the altar of burnt offering.