Matthew 18:15-17

¹⁵“If your brother sins, go and show him his fault in private; if he listens to you, you have won your brother. ¹⁶But if he does not listen to you, take one or two more with you, so that by the mouth of two or three witnesses every fact may be confirmed. ¹⁷If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector.