First Book of Paralipomenon (Author Compiled by Isaias and Esdras from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
24:19hae vices eorum secundum ministeria sua ut ingrediantur domum Domini et iuxta ritum suum sub manu Aaron patris eorum sicut praecepit Dominus Deus Israhel
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.