Exodus 29:35-37

35“Thus you shall do to Aaron and his sons, according to all that I have commanded you. Seven days you shall consecrate them.

36And you shall offer a bull every day as a sin offering for atonement. You shall cleanse the altar when you make atonement for it, and you shall anoint it to sanctify it.

37Seven days you shall make atonement for the altar and sanctify it. And the altar shall be most holy. Whatever touches the altar must be holy.