Apostolic Constitutions, Book VII 28
1But whosoever comes to you, let him be first examined, and then received: for you have understanding, and are able to know the right hand from the left, and to distinguish false teachers from true teachers. But when a teacher comes to you, supply him with what he wants with all readiness. And even when a false teacher comes, you shall give him for his necessity, but shall not receive his error. Nor indeed may you pray together with him, lest you be polluted as well as he. Every true prophet or teacher that comes to you is worthy of his maintenance, as being a labourer in the word of righteousness.