What is the meaning of "Eich Chatah Heililu"?
Rashi: Lament over it, and say "Eich Chatah."
Radak: Heililu is a command, or past tense. Chatah is past tense, for the accent is on the penultimate syllable.
Malbim: In addition to what was broken, you should lament over how it was broken - easily, not in war. This is a sign that it was via Hashgachah, due to their sins.
Why does it say "Eich Hifnah Oref Mo'av Bush"?
Malbim: A Gibor who fights, even if he is defeated, he has no shame, for he died the death of a Gibor. Mo'av immediately turned the back of their necks [to the enemy, and fled], like cowards. This is a great shame!
Why will people jest about Mo'av?
Malbim: They [fled immediately,] like women and weaklings.
Why will Mo'av be an anxiety to its surroundings?
Malbim: Others will realize that it was via Hashem's Hashgachah.
