Numbers 21:10-14

And the children of Israel set forward, and pitched in Oboth.

And they journeyed from Oboth, and pitched at Ije-abarim, in the wilderness which is before Moab, toward the sunrising.

From thence they removed, and pitched in the valley of Zared.

From thence they removed, and pitched on the other side of Arnon, which is in the wilderness that cometh out of the coasts of the Amorites: for Arnon is the border of Moab, between Moab and the Amorites.

Wherefore it is said in the book of the wars of the LORD, What he did in the Red sea, and in the brooks of Arnon,