Matthew 18:15-17

15 And if your brother does wrong to you, go, make clear to him his error between you and him in private: if he gives ear to you, you have got your brother back again.

16 But if he will not give ear to you, take with you one or two more, that by the lips of two or three witnesses every word may be made certain.

17 And if he will not give ear to them, let it come to the hearing of the church: and if he will not give ear to the church, let him be to you as a Gentile and a tax-farmer.