Mark 7:21-22
For from within out of the heart of men proceed wicked reasonings, adulteries, whoredoms, murders,
Luke 6:45
A good man, out of the good treasure of his heart, produceth what is good; and a wicked man, from the evil treasure in his heart, produceth that which is evil: for out of the abundance of the heart the mouth speaketh.
James 1:26
If any man thinks he is a religious character among you, and bridleth not his tongue, but deceiveth his own heart, this man's religion is vain.
James 3:5-8
So also the tongue is a little member, and proudly vaunts. Behold how great a pile of wood, a little fire kindleth!