Wherefore it is said in the book of the wars of the Lord
A history of wars in former times, which the Lord had suffered to be in the world; and which, as Aben Ezra thinks, reached from the times of Abraham and so might begin with the battle of the kings in his time, and take in others in later times, and particularly those of Sihon, king of the Amorites, and his conquests of some parts of Moab; and to this book, which might be written by some one of those nations, Moses refers in proof of what he here says:
what he did in the Red sea;
that is, what Sihon king of the Amorites did, or the Lord by him, "at Vaheb in Suphah", as the words may be rendered; either against a king, or rather city, of Moab, whose name was Vaheb, in the borders of the land of Moab, or how he destroyed that city Vaheb with a storm or terrible assault F12:
and in the brooks of Arnon:
some places situated on the streams of that river, which were taken by the Amorites from the Moabites, as the book quoted plainly testified.