A few months back, we had a brief debate over whether it was Twain or
Lincoln who said, "It is better to remain silent and thought a fool than to
speak up and remove all doubt."

"A man who has knowledge spares his words.  Even a fool when he holds his
peace is considered wise.  When he closes his lips, he is esteemed a man of
understanding." (Proverbs 17: 27-28)