And he poured of the anointing oil upon Aaron's head, and anointed him, to sanctify him.
Read Chapter 8
Cyril of Jerusalem
You must know that this chrism [chrismation] is prefigured in the Old Testament. When Moses, conferring on his brother the divine appointment, was ordering him high priest, he anointed him after he had bathed in water, and thenceforward he was called “christ” [“anointed”], clearly after the figurative Chrism. ...