Commonitorium Against Heresies that:
"Shun them as you would a viper, as you would a scorpion, as you would a basilisk, lest they smite you not only with their touch, but even with their eyes and breath. What is to shun?
Not so much as to eat with a person of this sort.
What is shun?
'If anyone,' says Saint John, 'come to you and bring not this doctrine...'.
What but the Catholic and Universal doctrine, which has continued one and the same through the several successions of ages by the uncorrupt tradition of the truth and so will continue forever '... receive him not into your house, neither bid him Godspeed, for he that biddeth him Godspeed communicates with him in his evil deeds'.
Profane novelties of words.
What words are these?
Such as have nothing sacred, nothing religious, words utterly remote from the inmost sanctuary of the Church which is the temple of God; profane novelties of words, that is, of doctrines, subjects, opinions, such as are contrary to antiquity and the faith of the olden time".