For there is a fire gone out of Heshbon— The poet here rises into raptures, and prophesies the conquest of the whole country by the desolating army of Sihon marching out of Heshbon: for by fire is meant desolating war, to which it is most fitly compared: so in Judges 9:20. Isaiah 29:6. Amos 1:4. & seq.; and the same comparison is used by other authors.
——Quis Trojae nesciat urbem, Et tanti incendia belli.— VIRGIL.
The poet goes on, It hath consumed Ar of Moab, speaking of it, in a poetical enthusiasm, as present to his view, and already accomplished, though it never came to pass; for Ar remained in possession of Moab in Moses's time, Deuteronomy 18:22. This city was situated on the south side of the river Arnon, and became the capital of Moab, otherwise called Rabbah, or Rabbah-Mobah, i.e. the great city of Moab. It is thought to be the same as had the name of Areopolis in latter ages; see Bochart's Preface to his Phaleg. What we render high places, in the next clause of the verse, some take to be the name of a city or village; namely, Bamoth, mentioned Numbers 21:19 as situate in the country of Moab. According to our version, the clause signifies, the princes of Moab, who dwelt in the strongest forts of their country, lying on the river Arnon. The Arabic understands it of the Gods of those high places.