Numbers 21:26

The city of Sihon: this is added as a reason why Israel took possession of this land, notwithstanding God's prohibition of meddling with them or their land, Deuteronomy 2:9, because it was not now the land of the Moabites, but had been some time since taken from them, and in the possession of the Amorites. The former king of Moab, i.e. the predecessor of Balak, who was the present king.