The heart of the wise teacheth his mouth, and addeth learning to his lips.
– Proverbs 16:23
The use of heart here refers to the mind, as is common in Proverbs. The first phrase means that wisdom informs and constrains speech. Wise speech is a mark of a wise heart (Proverbs 15:28). The word for learning includes the idea of persuasion. This proverb is akin to verse 21 and highlights the worth of listening to wisdom (Proverbs 22:17-18).