He that hath knowledge spareth his words: and a man of understanding is of an excellent spirit.
– Proverbs 17:27
The word for spareth means restrain, as you would expect. The proverb commends careful speech. The sparing of words is not an effort to appear to have knowledge, or to acquire it. The word for knowledge means discernment and skill. Knowledge controls the tongue, rather than spewing out what comes to mind (Proverbs 15:28). The person without control of the tongue invites destruction (Proverbs 13:3). Control of the tongue can keep us from damaging relationships and even sin (Proverbs 11:12-13; 10:19). The second phrase expands the control to the temper (Proverbs 16:32). Wisdom is seen in appeasing and dampening strife, but folly excites it, and often through the tongue (Proverbs 14:29; 15:18; 19:11).