Matthew 12:34-35

How can ye, evil as ye are, 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 with psalms, hymns, spiritual songs, in grace singing in your hearts to God;

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
How can ye, evil as ye are, 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 with psalms, hymns, spiritual songs, in grace singing in your hearts to God;