Exodus 29:6-9

and thou shalt put the mitre upon his head, and put the holy crown upon the mitre. Then shalt thou take the anointing oil, and pour it upon his head, and anoint him. And thou shalt bring his sons, and put coats upon them. And thou shalt gird them with girdles, Aaron and his sons, and put the bonnets on them: and the priest's office shall be their's for a perpetual statute: and thou shalt consecrate Aaron and his sons.