Exodus 29:30, 35, 37

For seven days the one of his sons who is priest in his stead shall put them on when he enters the tent of meeting to minister in the holy place.

“Thus you shall do to Aaron and to his sons, according to all that I have commanded you; you shall ordain them through seven days.

For seven days you shall make atonement for the altar and consecrate it; then the altar shall be most holy, and whatever touches the altar shall be holy.