James 5:13 exhorts those who are merry to sing psalms, and none would suggest that the Psalter was excluded. It is noteworthy that he does this immediately after exhorting those in trouble to pray. This shows that, just as in the temple, singing is a religious duty distinct from prayer, even if in some respects they overlap.

Sing a New Song: Recovering Psalm Singing for the Twenty-First Century, Loc. 1870.