Numbers 21:13-15

NHEB(i) 13 From there they traveled, and camped on the other side of the Arnon, which is in the wilderness, that comes out of the border of the Amorites: for the Arnon is the border of Moab, between Moab and the Amorites. 14 Therefore it is said in the Book of the Wars of the LORD, "Waheb in Suphah, the valleys of the Arnon, 15 the slope of the valleys that incline toward the dwelling of Ar, leans on the border of Moab."