Bible: 1 Cor 5:9-11
5:9 I wrote you in my letter not to associate with sexually immoral people. 5:10 In no way did I mean the immoral people of this world, or the greedy and swindlers and idolaters, since you would then have to go out of the world. 5:11 But now I am writing to you not to associate with anyone who calls himself a Christian 1 who is sexually immoral, or greedy, or an idolater, or verbally abusive, 2 or a drunkard, or a swindler. Do not even eat with such a person.