Jesus Christ wants his followers to worship him from the heart.   Under the old law (Old Testament) worship was based on external instruments including literal sacrifices for sins, ceremonies, feasts, and the use of instruments for song during worship. In Hebrews 8:10 the writer reminds the Christians of the time of the prophesy (Jeremiah 31:31-34) that Christ was going to change their worship from external to internal:

10This is the covenant I will make with the house of Israel
       after that time, declares the Lord.
   I will put my laws in their minds
       and write them on their hearts.
   I will be their God,
       and they will be my people. (NIV)

It is this internal worship, or singing from the heart, that is a part of our worship today.  We use songs in worship not just for listening to, but as a personal way to “Sing and make music in your heart to the Lord” (Ephesians 5:20 NIV).