Ephesians 4;29 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.
Often we don't realize what an impact our words can make on someone else, either to build them up or break them down. 'Think before you speak' can't be learned enough. We all slip up and need forgiveness but we must try to watch what we say. An encouraging word can be the highlight of someone's day. Everyone is going through something, big or small, and can use a compliment or just a word of acknowledgement. Words can also be destructive. I've seen the hurt and low self-esteem it creates in a friend of mine. Its just wrong.
Let your speech be like a good song on the radio that makes you and others feel good, otherwise just shut it off.