John Chrysostom — as excerpted in the Catena Aurea on Matthew 18:15-17

“(Hom. lx.) Having above given a severe sentence against those who were the cause of offence, making them to fear on all sides; so now that they to whom the offence is offered should not fall into the opposite fault of supineness and indifference, seeking to spare themselves in all things, and so be puffed up; the Lord here checks such a tendency, commanding that they be reproved, saying, If thy brother shall trespass against thee, go, tell him his fault between thee and him alone.”