Fourth Book of Kings (Author Compiled by Isaias and Jeremias from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
3:26quod cum vidisset rex Moab praevaluisse scilicet hostes tulit secum septingentos viros educentes gladium ut inrumperet ad regem Edom et non potuerunt
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.