a still tongue

The ability, tendency, or decision to remain silent until it is prudent or one has thought carefully about what one wants or needs to say. Used especially in the proverb "a still tongue makes a wise head." I felt anger surging up in me after her caustic comments, but I decided to keep a still tongue and not say something I would later regret. If I may offer some advice, you should try to refrain from discussing your personal affairs so openly and at such length. Remember, a still tongue makes a wise head. I try to teach all my pupils that still tongues make wise heads.