Deuteronomy 3:16-17

And the land from Gilead to the valley of the Arnon, with the middle of the valley as a limit, as far as the river Jabbok which is the limit of the country of the children of Ammon, I gave to the Reubenites and the Gadites; As well as the Arabah, with the river Jordan as their limit, from Chinnereth to the Salt Sea, under the slopes of Pisgah to the east.