To be qualified to serve God as priests, Aaron and his sons had to be sanctified, to be set apart by being marked out. The mark that set apart, sanctified, Aaron and his sons to be the priests was the filling of their hands with the offerings (v. 24 see note Exo. 28:411b), signifying the filling of the believers with the riches of Christ (Eph. 3:8) through their subjective experience of Him as the reality of the offerings (Heb. 10:5-10). The steps in sanctifying Aaron and his sons included the washing away of their uncleanness (v. 4), the covering of their nakedness by the priestly garments (vv. 5-9), the dealing with their sinful nature through the sin offering (vv. 10-14), and the feeding of God and the priests with the burnt offering (vv. 15-18) and the peace offering (vv. 19-28). This was not merely a consecration or ordination of Aaron and his sons. See also note Exo. 29:281.