Matthew 12:33-37 (NRSV)
Either make the tree good, and its fruit good; or make the tree bad, and its fruit bad; for the tree is known by its fruit. You brood of vipers! How can you speak good things, when you are evil? For out of the abundance of the heart the mouth speaks. The good person brings good things out of a good treasure, and the evil person brings evil things out of an evil treasure. I tell you, on the day of judgment you will have to give an account for every careless word you utter; for by your words you will be justified, and by your words you will be condemned."