Ordination, as a practice, is clearly set forth in the Bible. In the Old Testament, Aaron and his sons were chosen by God to serve as priests (Exodus 28:1), and they were specifically ordained for this responsibility:
“Then Moses took some of the anointing oil and some of the blood which was on the altar, and sprinkled it on Aaron, on his garments, on his sons, and on the garments of his sons with him; and he consecrated Aaron, his garments, his sons, and the garments of his sons with him” (Leviticus 8:30).
Quoting from the NASB:
“‘The holy garments of Aaron shall be for his sons after him, that in them they may be anointed and ordained’” (Exodus 29:29).
The priestly responsibility was to serve as God’s representative to the Israelites. Note Malachi 2, verse 7:
“‘For the lips of a priest should keep knowledge, And people should seek the law from his mouth; For he is the messenger of the LORD of hosts.’”
The Book of Hebrews speaks of the duties of the High Priest and shows that God commissions this office:
“For every high priest taken from among men is appointed for men in things pertaining to God, that he may offer both gifts…