Números 21:13

13 They set out from there and camped alongside the Arnon, which is in the wilderness extending into Amorite territory. The Arnon is the border of Moab, between Moab and the Amorites.

13 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.