Second Book of Paralipomenon (Author Compiled by Isaias and Esdras from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
30:21feceruntque filii Israhel qui inventi sunt in Hierusalem sollemnitatem azymorum septem diebus in laetitia magna laudantes Dominum per singulos dies Levitae quoque et sacerdotes per organa quae suo officio congruebant
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.