Mark 7:21-22
For within, out of the heart of men, proceed evil reasonings, adulteries, fornications, murders,
Luke 6:45
The good man out of the good treasure of his heart brings forth the good; and the wicked man out of the wicked treasure of his heart brings forth that which is wicked: for out of the abundance of his heart his mouth speaks.
James 1:26
But if any one seems to be religious, bridling not his own tongue, but deceiving his own heart, the religion of that man is vain.
James 3:5-8
so also the tongue is a little member, and it boasts great things. Behold, how great a wood a little fire kindles!