A fool uttereth all his mind: but a wise man keepeth it in till afterwards.
Proverbs 29:11
King James Version (public domain)
Traditionally attributed to Solomon · c. 10th century BC · King of Israel, renowned for wisdom
Context
9If a wise man contendeth with a foolish man, whether he rage or laugh, there is no rest.
10The bloodthirsty hate the upright: but the just seek his soul.
11A fool uttereth all his mind: but a wise man keepeth it in till afterwards.
12If a ruler hearken to lies, all his servants are wicked.
13The poor and the deceitful man meet together: the LORD lighteneth both their eyes.