Numbers 21:14-16, 27-30

That is why the Book of the Wars of the LORD says: “… and Waheb in Suphah, and the ravines, the Arnon, and the slopes of the ravines that lead to the settlement of Ar. These places are at the border of Moab.” The Israelites went from there to Beer; a well is there where the LORD said to Moses, “Gather the people and I will give them water.”

That is why the poets say: “Come to Heshbon and rebuild it; rebuild Sihon’s city. A fire began in Heshbon; flames came from Sihon’s city. It destroyed Ar in Moab, and it burned the Arnon highlands. How terrible for you, Moab! The people of Chemosh are ruined. His sons ran away and his daughters were captured by Sihon, king of the Amorites. But we defeated those Amorites. We ruined their towns from Heshbon to Dibon, and we destroyed them as far as Nophah, near Medeba.”