Matthew 18:15-17

15“If your brother sins against you, go tell him his fault, between you and him alone. If he listens to you, you have won your brother.

16But if he won’t listen, take one or two others with you, so that by the testimony of two or three witnesses every fact may be established.

17If he doesn’t pay attention to them, tell the church. If he doesn’t pay attention even to the church, let him be like a Gentile and a tax collector to you.