Hebrews 7:4, 8, 13, 15, 18

Now pause and consider how great this man was to whom Abraham, the patriarch, gave a tenth of the spoils.

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].

For the One of whom these things are said belonged [not to the priestly line of Levi but] to another tribe, from which no one has officiated or served at the altar.

And this becomes even more evident if another priest arises in the likeness of Melchizedek, [Ps 110:4]

For, on the one hand, a former commandment is cancelled because of its weakness and uselessness [because of its inability to justify the sinner before God]