8 And he placed the breastplate upon him: and in the breastplate he put the Urim and the Thummim. 9 And he set the mitre upon his head; and upon the mitre, in front, did he set the golden plate, the holy crown; as Jehovah commanded Moses. 10 And Moses took the anointing oil, and anointed the tabernacle and all that was therein, and sanctified them. 11 And he sprinkled thereof upon the altar seven times, and anointed the altar and all its vessels, and the laver and its base, to sanctify them. 12 And he poured of the anointing oil upon Aaron's head, and anointed him, to sanctify 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.