Exodus 29:35-37

29:35 “Thus you are to do for Aaron and for his sons, according to all that I have commanded you; you are to consecrate them for seven days. 29:36 Every day you are to prepare a bull for a purification offering for atonement. You are to purge the altar by making atonement for it, and you are to anoint it to set it apart as holy. 29:37 For seven days you are to make atonement for the altar and set it apart as holy. Then the altar will be most holy. Anything that touches the altar will be holy.

Leviticus 8:33

8:33 And you must not go out from the entrance of the Meeting Tent for seven days, until the day when your days of ordination are completed, because you must be ordained over a seven-day period.