Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 22

Chapter 22.—Of Abraham’s Overcoming the Enemies of Sodom, When He Delivered Lot from Captivity and Was Blessed by Melchizedek the Priest.

Having received this oracle of promise, Abraham migrated, and remained in another place of the same land, that is, beside the oak of Mamre, which was Hebron.  Then on the invasion of Sodom, when five kings carried on war against four, and Lot was taken captive with the conquered Sodomites, Abraham delivered him from the enemy, leading with him to battle three hundred and eighteen of his home-born servants, and won the victory for the kings of Sodom, but would take nothing of the spoils when offered by the king for whom he had won them.  He was then openly blessed by Melchizedek, who was priest of God Most High, about whom many and great things are written in the epistle which is inscribed to the Hebrews, which most say is by the Apostle Paul, though some deny this.  For then first appeared the sacrifice which is now offered to God by Christians in the whole wide world, and that is fulfilled which long after the event was said by the prophet to Christ, who was yet to come in the flesh, “Thou art a priest for ever after the order of Melchizedek,” 908 —that is to say, not after the order of Aaron, for that order was to be taken away when the things shone forth which were intimated beforehand by these shadows.

Footnotes

Ps. 110.4.