Our Savior received a bodily anointing and so became a true king and a true priest. Both king and priest he was of his very self; a savior could be nothing less. Hear in his own words how he himself became a king: I have been appointed king by God on Zion his holy mountain. Hear in the Father’s words that he was a priest: You are a priest for ever in the line of Melchizedek. Aaron was the first under the law to be made a priest by being anointed with chrism, yet the Father does not say, “in the line of Aaron,” lest it be believed that the Savior’s priesthood could be passed on by inheritance, for at that time Aaron’s priesthood was transmitted by lineal descent. But the Savior’s priesthood is not inherited because this priest lives on for ever. Therefore Scripture says: You are a priest for ever in the line of Melchizedek.
From a treatise on the Trinity by Faustus Luciferanus, priest