BOOK Five must have been united with Book Four as a Five must have been united with Book Four as a separate collection. This is evident from the fact first, that the psalm which begins Book Five (Psalm 107) closely resembles in style and thought the two psalms which close Book Four. The three psalms, 105, 106, 107, clearly belong together. Furthermore, Books Four and Five, both use the name JHWH for God instead of Elohim which is the preferred name for God in Books Two and Three. (See introduction to Book Four.)
Book Five contains three special groups of psalms which must have been collected separately: a) the Hallel psalms, 113‐ 118; b) the Songs of Ascent, 120-134; c) the Hallelujah psalms, 135-150.