Matthew 12:34 NIV

1 Samuel 24:13 NIV
As the old saying goes, ‘From evildoers come evil deeds, ’ so my hand will not touch you.

Ephesians 4:29 NIV
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen.

James 3:5-8 NIV
Likewise, the tongue is a small part of the body, but it makes great boasts. Consider what a great forest is set on fire by a small spark. The tongue also is a fire, a world of evil among the parts of the body. It corrupts the whole body, sets the whole course of one’s life on fire, and is itself set on fire by hell. All kinds of animals, birds, reptiles and sea creatures are being tamed and have been tamed by mankind, but no human being can tame the tongue. It is a restless evil, full of deadly poison.

Luke 6:45 NIV
A good man brings good things out of the good stored up in his heart, and an evil man brings evil things out of the evil stored up in his heart. For the mouth speaks what the heart is full of.

Matthew 15:18 NIV
But the things that come out of a person’s mouth come from the heart, and these defile them.