Proverbs 12:23 in the World English Bible
A prudent man keeps his knowledge, but the hearts of fools proclaim foolishness.
Context
22 Lying lips are abomination to the LORD: but they that deal truly are his delight.
23 A prudent man concealeth knowledge: but the heart of fools proclaimeth foolishness.
24 The hand of the diligent shall bear rule: but the slothful shall be under tribute.