The text of this type of nonmetrical hymn is taken from Biblical text other than the Book Of Psalms
[DOC] [TLE] PSALMS OF JOY AND SORROW - Naxos [PAR] "In the Torah and the [books of the] Prophets," wrote biblical scholar Nahum 
Sarna ... or songs in other Hebrew biblical books (e.g., shirat hayam [Song of the 
Sea], ... And although a number of individual Psalms would not fall into that 
category ... in this present canonized form of the Masoretic text contains 150 
Psalmsthe... [DOC] [TLE] Glossary of Sacred Music Terminology - MusicaSacra Church Music Forum [PAR] Most