Matthew 7:16-20

16By their fruit you will recognize them. Are grapes gathered from thornbushes, or figs from thistles? 17Likewise, every good tree bears good fruit, but a bad tree bears bad fruit. 18A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. 19Every tree that does not bear good fruit is cut down and thrown into the fire. 20So then, by their fruit you will recognize them.