John Wesley on Matthew 7:18

A good tree cannot bring forth evil fruit, neither a corrupt tree good fruit - But it is certain, the goodness or badness here mentioned respects the doctrine, rather than the personal character. For a bad man preaching the good doctrine here delivered, is sometimes an instrument of converting sinners to God. Yet I do not aver, that all are true prophets who speak the truth, and thereby convert sinners. I only affirm, that none are such who do not.