Deuteronomy 2:18

Thou art to pass over through Ar, the coast of Moab, this day:

This was God's direction to Israel to pass through Ar, the district belonging to Moab. The command forbade fighting the Moabites or seizing any of their territory. The reason was that God had given Ar to the descendants of Lot as their own possession. Israel therefore kept to the east of Moab while moving northward toward the promised land.