Numbers 21:13-15

From thence they journeyed, and encamped on the other side of the Arnon, which is in the wilderness, that cometh out of the border of the Amorites: for the Arnon is the border of Moab, between Moab and the Amorites. Wherefore it is said in the book of the Wars of Jehovah, Vaheb in Suphah, And the valleys of the Arnon, And the slope of the valleys That inclineth toward the dwelling of Ar, And leaneth upon the border of Moab.