The Book of Psalms is a book in the Bible made up of 150 Hebrew poems called Psalms. The Book of Psalms is part of the Old Testament and can be heard during mass after the first reading. People traditionally believe that many of the Psalms were written by King David to God. Perhaps the most famous one is Psalm 23, which starts "The LORD is my shepherd". Psalm 23 is often used for funerals.