Offerings, Priest Ordination and the Death of Nadab and Abihuby KalebRosendahl

Leviticus 8:12

And he poured of the anointing oil upon Aaron’s head, and anointed him, to sanctify him.

The pouring of anointing oil upon Aaron's head consecrated and sanctified him as high priest. That sacred anointing was the act by which he was set apart to the holy office. By it he was appointed to the priesthood that God had entrusted to him and his family.