Albert Barnes Commentary Matthew 18:34

"And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due." — Matthew 18:34 (ASV)

Delivered him to the tormentors. The word tormentors, here, probably means keepers of the prison.

Torments were inflicted on criminals, not on debtors. Such torments included stretching the limbs, pinching the flesh, taking out the eyes, or taking off the skin while alive, and so on.

It is not probable that anything of this kind is intended here, but only that the servant was punished by imprisonment until the debt should be paid.