John Chrysostom

How? "For he was yet in his loins when Melchisedec met him," i.e. Levi was in him, although he was not yet born. And he said not the Levites but Levi. Hast thou seen the superiority? Hast thou seen how great is the interval between Abraham and Melchisedec, who bears the type of our High Priest? And he shows that the superiority had been caused by authority, not necessity. For the one paid the tithe, which indicates the priest: the other gave the blessing, which indicates the superior. …

Homily on Hebrews 12 ↗

Theophylact of Ohrid

So that the priests of the law could not say: what relation does it have to us if Abraham gave a tithe? – he says that through the mediation of Abraham, Levi too, the forefather of our priesthood, "who receives tithes,... paid tithes." Thus, is not Melchizedek superior even to Levi, when he evidently received a tithe from him as well, through the mediation of Abraham? The expression "so to speak" either means: to put it briefly, or instead of: so I will say. …

Commentary on Hebrews ↗

Oecumenius

"and so to speak." So that they may not say, "And what," he says, "was also tithing through Abraham?" Yes, he says. For Levi was in Abraham when he gave the tithes, even though he was not yet born. If therefore Levi was in the loins of Abraham when he gave the tithes, it is clear that Levi himself, the ancestor of the priests, gave tithes, when Abraham gave tithes. And the phrase, so to speak, means this, that, in short, or instead of saying, let me put it this way. …

The Pseudo-Oecumenian Catena on Hebrews ↗

Augustine of Hippo

We now advance in reply to such as argue that one who is born of a baptized man ought himself to be regarded as already baptized. "For why," they ask, "could he not have been baptized in the loins of his father, when, according to the Epistle to the Hebrews, Levi was able to pay tithes in the loins of Abraham?" They who propose this argument ought to observe that Levi did not on this account subsequently not pay tithes, because he had paid tithes already in the loins of Abraham, but because he was ordained to the office of the …

On The Merits And Forgiveness Of Sins And On Infant Baptism 2.39 ↗

Thomas Aquinas

345. – Then when he says, and one might say that even Levi who received tithes, paid tithes through Abraham, he answers an objection. For someone might say: it is true that Melchizedek is greater than Abraham who gave him tithes; but Levi is greater than Melchizedek. So the Apostle says that this is not valid, because one might say that through Abraham, i.e., through the medium of Abraham, even Levi paid tithes to him who received them, i.e., to Melchizedek. Therefore, he is still greater than Levi. …

Commentary on Hebrews ↗