Matthew 12:35-37
A good man out of the good treasure of his heart bringeth forth good things: and a wicked man out of the evil treasure of his heart bringeth forth evil things.
Hebrews 4:12-13
For the word of God is quickening, and energetic, and sharper than every two-edged sword, and piercing through and through, so as to divide both soul and spirit, both joints and spinal marrow, and critically judges the thoughts and intents of the heart.
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 3:2-10
For in many things we all offend. If any man offend not in word, he is a perfect man, and capable of reining in the whole body.