Exodus 30:10 And Aaron shall make an atonement upon the horns of it once in a year with the blood of the sin offering of atonements: once in the year shall he make atonement upon it throughout your generations: it is most holy unto the Lord. 12 I MC VC

Leviticus 16:18 And he shall go out unto the altar that is before the Lord, and make an atonement for it; and shall take of the blood of the bullock, and of the blood of the goat, and put it upon the horns of the altar round about. 20 I MC VC

Leviticus 16:19 And he shall sprinkle of the blood upon it with his finger seven times, and cleanse it, and hallow it from the uncleanness of the children of Israel. 20 I MC VC