John Chrysostom

What then, if the tares should remain until the end? "Then I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them." He again reminds them of John's words, introducing Him as judge; and He saith, So long as they stand by the wheat, we must spare them, for it is possible for them even to become wheat; but when they have departed, having profited nothing, then of necessity the inexorable punishment will overtake them. …

Homily on the Gospel of Matthew 46 ↗

Augustine of Hippo

It may be asked why He commands more than one bundle or heap of tares to be formed? Perhaps because of the variety of heretics differing not only from the wheat, but also among themselves, each several heresy, separated from communion with all the others, is designated as a bundle; and perhaps they may even then begin to be bound together for burning, when they first sever themselves from the Catholic communion, and begin to have their independent church, so that it is the burning and not the binding into …

Catena Aurea by Aquinas ↗

Jerome

But what is said, 'Lest while you gather up the tares, you root up also the wheat together with them,' gives place to repentance, and we are warned not to cut off our brother immediately, because it may happen that he who is corrupt in his understanding today, may tomorrow begin to be sound and to defend the truth. …

Commentary on Matthew ↗

Thomas Aquinas

But will they always be spared? No, but until a time; hence he says, let both grow until the harvest etc. A similar statement is found in Apocalypse 22:11: he that hurts, let him hurt still; and he that is filthy, let him be filthy still. Let both grow until the harvest. Against this statement it is objected that Isaiah 1:16 says: take away the evil of your thoughts etc. Likewise, 1 Corinthians 5:7: purge out the old leaven, that you may be a new lump, as you are unleavened etc. What then does he mean by let them be etc.? …

Commentary on Matthew ↗