Matthew 12:34

You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speaks.

Ephesians 4:29

Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear.

Luke 6:45

The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.