Zephaniah 2:9
Therefore as I live, saith the LORD of hosts, the God of Israel, Surely Moab shall be as Sodom, and the children of Ammon as Gomorrah, even the breeding of nettles, and saltpits, and a perpetual desolation: the residue of my people shall spoil them, and the remnant of my people shall possess them.
The first two chapters form a warning message that is now being given to the world, and the light that is rejected from that message brings condemnation.
Moab and Ammon were enemies of God's people in ancient times, and they represent the enemies of His faithful people through all ages.
The promise that the residue of His people shall spoil them and the remnant of His people shall possess them prophesies the time when the wicked are utterly and finally removed from the earth. At that time places of sin give way to places of righteousness, and the dwelling places of sin are replaced with homes of righteousness. The remnant's possession of the land of Moab and Ammon thus points to the righteous inheriting the restored earth.