John Chrysostom

"Remember them that are in bonds, as bound with them, them which suffer adversity as being yourselves also in the body."

Homily on Hebrews 33 ↗

Theophylact of Ohrid

"Remember those who are in prison, as though you were in prison with them" — For he who is bound to someone, even if he wished to forget, cannot. "And of those who suffer, as you yourselves also are in the body" — "The suffering" — whether in prisons, or in hunger, or in some other calamity. For whoever reflects that he too is clothed in a similar body will defend them, on the one hand out of sympathy, and on the other out of fear lest he himself, for his lack of compassion, should fall into similar calamities.

Commentary on Hebrews ↗

Oecumenius

"as bound." For he who is bound to someone, even if he wishes to forget, cannot. "and those who suffer adversity." Of those who are suffering either in prisons, or in famine, or in another affliction. For if someone were to consider that he himself is surrounded by a body that suffers similarly, he would have more compassion for them, both because of sympathy, and because of the fear that he too might experience similar sufferings from inhumanity.

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

He says, Remember them that are in prison, i.e., those who for the love of God were sent to prison. Remember them by visiting and redeeming, as though in prison with them: 'I was in prison and you visited me' (Mt. 25:36). Against this Isaiah (14:27) says: 'I opened not the prison to his prisoners.' But they did this sometimes, as is clear from Hebrews (10:34). But it particularly pertains to a work of mercy to regard another's suffering as one's own. …

Commentary on Hebrews ↗