Exodus 29:30, 35, 37

That son who is [high] priest in his place shall put them on [each day for] seven days when he comes into the Tent of Meeting to minister in the Holy Place.

“So you shall do to Aaron and to his sons in accordance with all I have commanded you; during seven days you are to ordain them.

For seven days you shall make atonement for the altar [of burnt offering] and consecrate it; then the altar shall be most holy. Whatever touches the altar must be holy (set apart for God’s service).