If you have nothing nice to say then it is better for you to keep silence. It is better for you to be silent and avoid committing a mistake in saying hurting words. Words spoken can no longer be taken back. Words are not like water which can be aspirated if there is still time. So , be careful what you utter; think a hundred times before deciding to let those words come out from your mouth.

One author said, "let the words of inspiration come out from your mouth. Let them be an inspiration for those who're weary and discouraged." Doing such good thing will help them grow stronger. You become a blessing to them who need hope and peace by speaking words of inspiration. "Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear."(Ephesians 4:29)http://www.openbible.info/topics/hurtful_words.

 

On the other hand, your words can do far greater damage in the lives of those who hear them if you are not careful. Be careful not to say what you don't intend to speak. If you hurt others with your  words, glorify not because you become the stumbling block of happiness and peace in  their lives.