8 Then he put the breastplate on him, and he put the Urim and the Thummim in the breastplate. 9 And he put the turban on his head. Also on the turban, on its front, he put the golden plate, the holy crown, as the Lord had commanded Moses. 10 Also Moses took the anointing oil, and anointed the tabernacle and all that was in it, and consecrated them. 11 He sprinkled some of it on the altar seven times, anointed the altar and all its utensils, and the laver and its base, to consecrate them. 12 And he poured some of the anointing oil on Aaron's head and anointed him, to consecrate him.
Matthew Henry's Commentary on Leviticus 8:8-12
Commentary on Leviticus 8:1-13
(Read Leviticus 8:1-13)
The consecration of Aaron and his sons had been delayed until the tabernacle had been prepared, and the laws of the sacrifices given. Aaron and his sons were washed with water, to signify that they ought to purify themselves from all sinful dispositions, and ever after to keep themselves pure. Christ washes those from their sins in his own blood whom he makes kings and priests to our God, Hebrews 10:22. The anointing of Aaron was to typify the anointing of Christ with the Spirit, which was not given by measure to him. All believers have received the anointing.