Cyril of Alexandria — as excerpted in the Catena Aurea on Luke 12:8-12

“But if our Saviour means to imply, that if any injurious word is spoken by us against a common man, we shall obtain pardon if we repent, there is no difficulty in the passage, for since God is by nature merciful, He restores those who are willing to repent. But if the words are referred to Christ how is he not to be condemned who speaks a word against Him?”