A prudent man concealeth knowledge (Proverbs 12:16; Proverbs 10:14). He is not wont to utter unadvisedly what he knows, but waits for fitting opportunity, either from humility or wise caution. Of course, in some cases reticence is sinful.
The LXX; reading the passage differently, renders, "A prudent man is the seat of intelligence ( θρόνος αἰσθήσεως)." The heart of fools proclaimeth foolishness (Proverbs 13:16; Proverbs 15:2). A foolish man cannot help exposing the stupid ideas that arise in his mind, which he considers wisdom.
Septuagint, "The heart of fools shall meet with curses."