Leviticus 16:18-19
18 Then he will go out to the altar that is before the Lord and make atonement for it. He is to take some of the bull’s blood and some of the goat’s blood and put it on the horns on all sides of the altar.
19 He is to sprinkle some of the blood on it with his finger seven times to cleanse and set it apart(A) from the Israelites’ impurities.(B)