Hebrews 7:4

"Now consider" (saith he) "how great this man is to whom even the Patriarch Abraham gave the tenth of the spoils." Up to this point he has been applying the type: henceforward he boldly shows him Melchisedec to be more glorious than the Jewish realities. But if he who bears a type of Christ is so much better not merely than the priests, but even than the forefather himself of the priests, what should one say of the reality? Thou seest how super-abundantly he shows the superiority. "Now consider" (he says) "how great this man is to whom even the Patriarch Abraham gave a tenth out of the choice portions." Spoils taken in battle are called "choice portions." And it cannot be said that he gave them to him as having a part in the war, because (he said) he met him "returning from the slaughter of the kings," for he had staid at home (he means), yet Abraham gave him the first-fruits of his labors.

"Consider how great this man was." Since he applied the type to the truth, he wishes to show that the type of Christ himself, namely Melchizedek, was greater than those priests among the Jews. And what do I say about the priests? He was indeed greater than the patriarch Abraham himself. If the type of Christ, he says, is greater than the patriarch himself, what then could anyone say about Christ? In one way, Abraham was greater than Melchizedek, but the type was the one who conquers. Thus, Cyril among the saints in the second book concerning On Adoration in Spirit and Truth… "'to whom even the patriarch Abraham gave a tenth.' It is not to be said, he says, that he gave him tithes, as one who has shared in the war; (for this is why he said above, 'who met Abraham returning from the slaughter), but according to reverence and honor, just as giving first fruits. 'gave a tenth of the spoils.' From the loot and plunder. And if he is greater than the patriarch (and this is indicated by the giving of tithes), much more than those among the Jewish priests. For the patriarch is not brought forth without reason: but to show that if the patriarch, he says, has given, what is to be said about the priests?"

This Melchizedek is Shem, who became a king due to his greatness; he was the head of fourteen nations. In addition, he was a priest. He received this from Noah, his father, through the rights of succession. Shem lived not only to the time of Abraham, as Scripture says, but even to the time of Jacob and Esau, the grandsons of Abraham. It was to him that Rebekah went to ask and was told, "Two nations are in your womb, and the elder shall serve the younger." Rebekah would not have bypassed her husband, who had been delivered at the high place, or her father-in-law, to whom revelations of the divinity came continually, and gone straight to ask Melchizedek unless she had learned of his greatness from Abraham or Abraham's son. Abraham would not have given him a tenth of everything unless he knew that Melchizedek was infinitely greater than himself. Would Rebekah have asked one of the Canaanites or one of the Sodomites? Would Abraham have given a tenth of his possessions to any one of these? One ought not even entertain such ideas.Because the length of Melchizedek's life extended to the time of Jacob and Esau, it has been stated, with much probability, that he was Shem. His father Noah was dwelling in the east, and Melchizedek was dwelling between two tribes, that is, between the sons of Ham and his own sons. Melchizedek was like a partition between the two, for he was afraid that the sons of Ham would turn his own sons to idolatry.