In the days of the ancients one thing that was very common and not discussed very much today. Almost everyone who believed that there was a God sang praises and hymns to him. There was no Bible, No Koran, nothing written like it is today. Song was always the way a family or person worshiped the Lord. The high priest of course had scrolls and such that they were privied to. But the common man and women had nothing like that. It was faith and word of mouth. In later text you see that David has a whole book devoted to Psalms which he sang as he played his musical instrument. These songs were scribed by some one who witnessed this normal way of life.