Matthew 12:35-37
A good man out of the good treasure of the heart produceth good things; and a wicked man out of the wicked treasure uttereth wicked things:
Hebrews 4:12-13
For the word of God is lively and efficacious, and sharper than any two-edged sword, piercing even to the dividing of soul and spirit, and of the very joints and marrow, and judging the thoughts and intentions of the heart.
James 1:26
If any among you seem to be religious, and bridleth not his tongue, but deceiveth his heart, this man's devotion is vain.
James 3:2-10
and if any offend not in word, he is a compleat man, able to manage also the whole body.