Cyril of Alexandria

Where thou wilt suffer want until thou payest the last farthing; and this is what He adds, I say unto you, thou shalt not depart hence.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

The Lord says this in order to bring the hardened to fear and urge them toward peace. He knows that the fear of loss and punishments humbles the earthly-minded more than anything else, and therefore He says this. They understand this speech as referring also to the devil. For he is our adversary. Therefore we, while still "on the way," that is, in this life, must endeavor, through the practice of virtue, to "be free of him" and to have nothing in common with him, so that at the future judgment he may not hand us over to the Judge. …

Commentary on Luke ↗

Bede

I tell you, you will not get out of there until you have paid the very last penny. That is, until you have paid for even the smallest sins. Because you will always be able to pay the penalties by suffering, but never able to obtain forgiveness in return (for there will be no place for forgiveness there), you will never come out from where you will bear the eternal penalties for your deeds.

On the Gospel of Luke ↗

Bonaventure

Therefore he adds: I say to you, you shall not go out from there until you have paid the last mite, that is, never, because you will never pay it back. Bede: "He always pays penalties by suffering for sins, but never by obtaining pardon." Hence until does not set a limit here, just as neither does it there: "The Lord said to my Lord, etc., until I place," etc. …

Commentary on Luke, Chapter 12 ↗