Mark 7:21-22
For from within, out of the heart of men, proceed the purposes which are evil: adulteries, lewd actions, murders,
Luke 6:45
The good man, out of the good treasury of his heart, brings forth that which is good; and the evil man, out of the evil treasury of his heart, brings forth that which is evil. For out of the abundance of his heart his mouth speaks.
James 1:26
If any one among you seems to be religious, and bridles not his tongue, but deceives his own heart, this man's religion is vain.
James 3:5-8
So, also, the tongue is a little member, and boasts great things. Behold, how great a forest does a little fire set in a blaze.