Main one is 1 Corinthians 5:11-13:
But now I am writing you to stop keeping company with anyone called a brother who is sexually immoral
or a greedy person or an idolater or a reviler or a drunkard or an extortioner, not even eating with such a man. For what do I have to do with judging those outside? Do you not judge those inside, while God judges those outside? “Remove the wicked person from among yourselves."