Numbers 21:13-15

Matthew(i) 13 And they departed thence and pitched on the other side of Arnon, which ryuer is in the wyldernesse, and cometh out of the costes of the Amorites: for Arnon is the border of Moab, betwen Moab & the Amorites. 14 Wherfore it is spoken in the boke of the warre of the Lorde: goo wyth vyolence, both on the ryuer of Arnon 15 and on the ryuers head, which shoteth downe to dwel at Ar, & leaneth vpon the costes of Moab.