Your words will reveal the hidden contents that are deep inside of your heart. 

Matthew12:34-37 For out of the abundance of the heart the mouth speaketh. A good man out of the good treasure of the heart bringeth forth good things:and an evil man out of the evil treasure bringeth forth evil things. But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment. For by thy words thou shalt be justified, and by thy words thou shalt be condemned.