Ambrose of Milan
Catena Aurea · Lukasevangelium 17
Lk 17, Verses 3–4English original
Take heed to yourselves: If thy brother trespass against thee, rebuke him; and if he repent, forgive him. And if he trespass against thee seven times in a day, and seven times in a day turn again to thee, saying, I repent; thou shalt forgive him.
After the parable of the rich man who is tormented in punishment, Christ added a commandment to give forgiveness to those who turn themselves from their trespasses, lest any one through despair should not be reclaimed from his fault; and hence it is said, Take heed to yourselves.