Hebrews 7:5-10

It is true that those descendants of Levi who are charged with the priestly office are commanded in the Law to collect tithes from the people—which means, from their kinsmen—though these have descended from Abraham. But this person [Melchizedek] who is not from their Levitical ancestry received tithes from Abraham and blessed him who possessed the promises [of God]. Yet it is beyond all dispute that the lesser person is always blessed by the greater one. Furthermore, here [in the Levitical priesthood] tithes are received by men who are subject to death; but in that case [concerning Melchizedek], they are received by one of whom it is testified that he lives on [perpetually]. A person might even say that Levi [the father of the priestly tribe] himself, who received tithes, paid tithes through Abraham [the father of all Israel and of all who believe], for Levi was still in the loins (unborn) of his forefather [Abraham] when Melchizedek met him (Abraham).