Third Book of Kings (Author Compiled by Isaias and Jeremias from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
1:30quia sicut iuravi tibi per Dominum Deum Israhel dicens Salomon filius tuus regnabit post me et ipse sedebit super solium meum pro me sic faciam hodie
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.