“Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother.”
Matthew 18:15 — Greek Interlinear
Church Fathers on Matthew 18:15
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.'
Our Lord admonishes us not to overlook one another’s faults, yet not so as seeking for matter of blame, but watching what you may amend. For our rebuke should be in love, not eager to wound, but anxious to amend. If you pass it by, you are become worse than he. He by doing you a wrong hath done himself a great hurt; you slight your brother’s wound, and are more to blame for your silence than he for his ill words to you.
He does not command us to forgive indiscriminately, but him only that will hearken and be obedient, and do penitence; that neither should forgiveness be unattainable, nor sufferance be too far relaxed.