II Thessalonians 3:6, 14

⁶Now we command you, brethren, in the name of our Lord Jesus Christ, that you keep away from every brother who leads an unruly life and not according to the tradition which you received from us.

¹⁴If anyone does not obey our instruction in this letter, take special note of that person and do not associate with him, so that he will be put to shame.