Matthew 18 - NRSV

If another member of the church sins against you, go and point out the fault when the two of you are alone. If the member listens to you, you have regained that one.
Matthew 18:15 sin speaking listening
If the member refuses to listen to them, tell it to the church; and if the offender refuses to listen even to the church, let such a one be to you as a Gentile and a tax collector.
Matthew 18:17 church sin listening

For where two or three are gathered in my name, I am there among them.
Matthew 18:20 Jesus community prayer
Then Peter came and said to him, “Lord, if another member of the church sins against me, how often should I forgive? As many as seven times?” Jesus said to him, “Not seven times, but, I tell you, seventy-seven times.”
Matthew 18:21-22 forgiveness neighbor sin