Second Book of Paralipomenon (Author Compiled by Isaias and Esdras from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
7:17tu quoque si ambulaveris coram me sicut ambulavit David pater tuus et feceris iuxta omnia quae praecepi tibi et iustitias meas iudiciaque servaveris
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.