Augustine of Hippo

But, inasmuch as they had prohibited the man from doing a thing in which, so far forth, he was really with them, the Lord said to them, "Forbid him not." For what they ought to have forbidden was what was outside their fellowship, so that they might bring him over to the unity of the Church, and not a thing like this, in which he was at one with them, that is to say, so far as he commended the name of their Master and Lord in the casting out of devils. …

Harmony Of The Gospels 4 ↗