Exodus 29:7-9

29:7 You are to take the anointing oil and pour it on his head and anoint him. 29:8 You are to present his sons and clothe them with tunics 29:9 and wrap the sashes around Aaron and his sons and put headbands on them, and so the ministry of priesthood will belong to them by a perpetual ordinance. Thus you are to consecrate Aaron and his sons.