Speak Good, or Keep Silent
To control our speech is a very important aspect in manifesting our belief also it is very important for our own spiritual development. If person wishes to say something, then if that speech is good, and will surely be rewarded for, then let him say it. And if not, then let him keep silent - whether it is apparent that the speech is Haram (forbidden) or Makrooh (disliked) or even Mubah (permissible). It is said that the permissible speech is to be left and avoided, and rather it is preferred to keep silent in such situations, out of fear that it may turn into something which is Haram or Makrooh.