Proverbs 17:28
Solomon points out that when a fool is silent, he is considered wise and full of understanding. It is only when we open our mouth that we remove all doubt! But the temptation to speak, at times, is overpowering. Whether it be in anger or to gossip, we can't seem to keep our words to ourselves.
It is beyond my ability to determine who is foolish or wise. However, the words that some speak clearly indicate the foolishness of their thoughts. Likewise, if I am still a fool, I consider it wise to keep my words restrained at times. For out of our heart are our thoughts and our words from our thoughts. David describes it best in Psalms 19:14 - Let the words of my mouth, and the meditation of my heart, be acceptable in thy sight, O LORD, my strength, and my redeemer.
If our heart is pure, our words will be acceptable to God. If not, we are but speaking foolishly. Silence the critics by silencing your words. More importantly, gain approval of the One that matters most by speaking only words led by Him.