1 Corinthians 3 is probably the clearest.
Cornelius a Lapide (famous Jesuit biblical commentator, respected by both Catholics and Protestants) has a good treatment here.
https://sites.google.com/site/aquinasstudybible/home/1-corinthians/cornelius-a-lapide-on-1-corinthians/chapter-1/chapter-2/chapter-3
Here are a few less common ones from Matthew that you might find interesting.
Matthew 5:21-26
>You have heard that it was said to them of old: Thou shalt not kill. And whosoever shall kill shall be in danger of the judgment. But I say to you, that whosoever is angry with his brother, shall be in danger of the judgment. And whosoever shall say to his brother, Raca, shall be in danger of the council. And whosoever shall say, Thou Fool, shall be in danger of hell fire. If therefore thou offer thy gift at the altar, and there thou remember that thy brother hath any thing against thee; Leave there thy offering before the altar, and go first to be reconciled to thy brother: and then coming thou shalt offer thy gift. Be at agreement with thy adversary betimes, whilst thou art in the way with him: lest perhaps the adversary deliver thee to the judge, and the judge deliver thee to the officer, and thou be cast into prison. Amen I say to thee, thou shalt not go out from thence till thou repay the last farthing.
One could argue that it is not speaking about a debt that is actually possible for one to pay (i.e. prison is strictly hell and not purgatory), but it seems more consistent with the passage to interpret this as purgatory, especially in context with with the different degrees of judgment/punishment outlined above. Cornelius a Lapide comments here,
>Note that there is here a Hebraism, and a parabolical form of expression, in which it is not necessary to adapt every word, but the general scope and meaning is what must be chiefly considered. And these, in this case, are rather hinted at than expressed. The sense then is this:—As a debtor, or one who is accused by a prosecutor before a judge, acts prudently if he agree with his adversary before judgment, and so escape the condemnation of the judge, prison, or infamy, so in like manner do thou act; and if thou hast injured thy brother in any way, as for instance by calling him raca, or a fool, thou hast made thyself a debtor, as it were, to restore him to honour: come in then, and be reconciled with him speedily, before thou be delivered as guilty to God the judge, who by a righteous vengeance shall deliver thee to prison, until thou shalt pay all thy debt. That prison is hell, or purgatory, according to the greater or less heinousness of thy sin. The word until, seems to bear a reference to purgatory, as though it signified terminable punishment, which is purgatory, whereas the punishment of hell has no end.
https://sites.google.com/site/aquinasstudybible/home/matthew-commentary/cornelius-a-lapide-on-matthew/chapter-1/chapter-2/chapter-3/chapter-4/chapter-5