Adam Clarke's Commentary on the Bible - Proverbs 17:28
Even a fool - He is counted wise as to that particular. He may know that he cannot speak well, and he has sense enough to keep from speaking. He is, as to that particular, a wise fool. A man may be golden-mouthed and silver-tongued in eloquence; but to know when and where to speak and to be silent, is better than diamonds. But who that thinks he can speak well can refrain from speaking? His tongue has no rest. read more
John Gills Exposition of the Bible Commentary - Proverbs 17:28
Even a fool, when he holdeth his peace, is counted wise ,.... Not only one that is sparing of his words, and is really a man of knowledge and understanding; but even a feel, if he is but silent, and does not betray his folly by his words, will be reckoned a wise man by those that do not know him; and, whatever fool he may be in other respects, yet in this he acts the wise part, that he holds his peace and says nothing; and he that shutteth his lips is esteemed a man of understanding ... read more