Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. Ephesians 4:29 NIV
The words we use and the way we use them reflect what is in our hearts. Even being around people who use foul language can have an impact on you. It is hard to watch a movie today and even TV at times where people use foul language. What goes in the mind can come out when you least expect it. I know, I have experienced it. I am not proud of it, but I thank God that He is a forgiving God.
Paul tells us what should be coming out of our mouths. We should be giving words of encouragement. Lifting others up and not tearing them down.