First Book of Paralipomenon (Author Compiled by Isaias and Esdras from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
28:20dixit quoque David Salomoni filio suo viriliter age et confortare et fac ne timeas et ne paveas Dominus enim Deus meus tecum erit et non dimittet te nec derelinquet donec perficias omne opus ministerii domus Domini
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.