2 Tesalonika 3:14-15

3:14 But if anyone does not obey our message through this letter, take note of him and do not associate closely with him, so that he may be ashamed. 3:15 Yet do not regard him as an enemy, but admonish him as a brother. ¹ 

[3:15]  ¹ tn That is, as a fellow believer.