Proverbs 16:23
"The heart of the wise teacheth his mouth, and addeth learning to his lips."
Cross References (ranked by relevance)
Proverbs 15:28
The heart of the righteous studieth to answer: but the mouth of the wicked poureth out evil things.
Colossians 3:16
Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.
Psalm 45:1
My heart is inditing a good matter: I speak of the things which I have made touching the king: my tongue is the pen of a ready writer.