Irenaeus

But as many as separate from the Church, and give heed to such old wives' fables as these, are truly self-condemned; and these men Paul commands us, "after a first and second admonition, to avoid.".
"Such was the horror which the apostles and their disciples had against holding even verbal communication with any corrupters of the truth; as Paul also says, "A man that is an heretic, after the first and second admonition, reject; knowing that he that is such is subverted, and sinneth, being condemned of himself."