The Lord called his people to treat the Moabites with the same kind of respect as they did to the descendants of Esau. For the land of Moab had been allotted to the descendants of Lot as a possession/inheritance, and thus was not part of Israel's Promised Land. Fighting, holy war or otherwise, was not to happen.
9 And the LORD said to me, ‘Do not harass Moab or contend with them in battle, for I will not give you any of their land for a possession, because I have given Ar to the people of Lot for a possession.’