The last two verses of the Gospel text aren't just a promise about small prayer groups. Jesus grants authority to the hierarchy in the Church to correct and discipline, He invokes the legal witness requirement of the Jewish tradition to establish a truth or judgment. The verse sits inside a passage about correcting a sinner within the community. Jesus applies the rabbinic language that conveys judicial authority to the apostles to govern the People of God, to make pronouncements about what is legally binding for the Christian people and what is not as the People of God, such as disciplinary matters, and also the authority to exclude people from the Christian community if they're not living according to the Christian way of life. In this text, if they're disobeying what the Church judges to be the way of life and how we ought to do things, this authority from the visible hierarchy is backed by Heaven itself having a divine origin, with Christ in their midst. We pray for all our spiritual leaders of the Church, that they may govern the house of God in truth, love, wisdom and mercy.