Matthew 18:16-20

But if you are unsuccessful, take one or two others with you and go back again, so that everything you say may be confirmed by two or three witnesses. If the person still refuses to listen, take your case to the church. Then if he or she won’t accept the church’s decision, treat that person as a pagan or a corrupt tax collector. “I tell you the truth, whatever you forbid on earth will be forbidden in heaven, and whatever you permit on earth will be permitted in heaven. “I also tell you this: If two of you agree here on earth concerning anything you ask, my Father in heaven will do it for you. For where two or three gather together as my followers, I am there among them.”