Ephesians 4:29

Do not let unwholesome (foul, profane, worthless, vulgar) words ever come out of your mouth, but only such speech as is good for building up others, according to the need and the occasion, so that it will be a blessing to those who hear (you speak).

What comes out of our mouths is a great indicator of what is in our hearts.  If we feel pain, joy, sadness, anger, love it all starts in our hearts and then we speak it.  If our heart has lost its balance and foundation from the Word what we speak will not align with the Word.  We no longer have the focus of Gods’ Word coming out of our mouths but we speak from the fleshly nature which leads to sin.