The theme of Psalmography is “making melody in our hearts to the Lord.”
A number of verses in the Bible discuss this concept, but here’s just a few. Though not stated as a commandment, the context is one of admonition for us to express thankfulness for everything the Lord has done for us.
“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. And whatever you do in word or deed, do all in the name of the Lord Jesus, giving thanks to God the Father through Him.”
–Colossians 3:16-17 (NKJV)
Another verse that describes our heart is contained in Paul’s letter to the Ephesians:
“…speaking to one another in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord, giving thanks always for all things to God the Father in the name of our Lord Jesus Christ, submitting to one another in the fear of God.”
–Ephesians 5:19-21 (NKJV)