2 John 10

and they sent this letter by them, “The apostles and the brothers who are elders, to the brothers in Antioch and Syria and Cilicia who are from the Gentiles, greetings.

Now I urge you, brothers, to keep your eye on those who cause dissensions and stumblings contrary to the teaching which you learned, and turn away from them.

Reject a factious man after a first and second warning,

For this reason, if I come, I will bring to remembrance his deeds which he does, unjustly disparaging us with wicked words. And not satisfied with this, he himself does not welcome the brothers either, and he forbids those who want to do so and puts them out of the church.