Numbers 22:2

And Balak, the son of Zippor, saw all that Israel had done to the Amorites. The Moabites had not interfered with the children of Israel while the latter journeyed along their eastern border, but had even sold them bread and water, Deuteronomy 2:29. At the same time, they seem to have entertained the hope that the mighty nation of the Amorites would easily overcome the invaders. This expectation was now rudely shattered.