Proverbs 12:23 - Joseph Benson’s Commentary on the Old and New Testaments

A prudent man concealeth knowledge He doth not vain- gloriously and unseasonably utter what he knows, but keeps it in his breast till he hath a fit occasion to bring it forth for God's glory, and the good of others; but the heart of fools proclaimeth foolishness The heart of a foolish man induces him to make ostentation of his knowledge, whereby he betrays his ignorance and folly.