Fourth Book of Kings (Author Compiled by Isaias and Jeremias from records of Nathan, Gad, Addo, Ahias, Jehu and others.)
Chapter 20
9cui ait Esaias hoc erit signum a Domino quod facturus sit Dominus sermonem quem locutus est vis ut accedat umbra decem lineis an ut revertatur totidem gradibus
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.