Matthew 12:34-35

Ye brood of vipers, how can ye, being evil, speak good things? For out of the abundance of the heart the mouth speaketh.

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 heart unto the Lord.

Treasury of Scripture Knowledge

Summary

The heart of the wise teacheth his mouth, and addeth learning to his lips.

Bible References

Heart

Matthew 12:34
Ye brood of vipers, how can ye, being evil, speak good things? For out of the abundance of the heart the mouth speaketh.
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 heart unto the Lord.