The passages in Jeremiah point to the restoration of the fortunes of Moab and Ammon, while Zephaniah’s prophecy at face value seems to point to a permanent destruction of these countries. It needs to be recognized, however, that the term for forever
can refer to a future of limited duration. As an example, Proverbs 10:25 speaks of the righteous person standing firm forever.
This is in reference to one’s entire life. See Exodus 19:9; Exodus 21:6; Deuteronomy 15:17; 1 Samuel 1:22; 1 Samuel 27:12 as further illustrations of the point. Thus, what Zephaniah has in view here is a long duration of desolation (see further 1 Samuel 27:12; Jeremiah 50:39–40).1
9 Therefore, as I live,” declares the LORD of hosts, the God of Israel, “Moab shall become like Sodom, and the Ammonites like Gomorrah, a land possessed by nettles and salt pits, and a waste forever. The remnant of my people shall plunder them, and the survivors of my nation shall possess them.”