Why does it say "Lachen Ko Amar Hashem"?
Malbim (2): Earlier, Yechezkel prophesized the punishment for Yisrael's neighbors for rejoicing over Yerushalayim's fall. Their punishments were different, for their sins were not the same. Tzor said "He'ach Nishberah Dalsos ha'Amim Nasebah Elai" (26:1; the trade and wealth of Yerushalayim will turn to me). Tzor's punishment was already told in a special Nevu'ah.
Why does it say "Ya'an b'Ya'an"?
Radak: It is repeated to strengthen the matter. The same applies to "Ya'an uv'Ya'an b'Mishpatai Ma'asu" (Vayikra 26:43).
What is the meaning of "Shamos v'Sha'of Eschem mi'Saviv"?
Rashi: Your neighbors were astounded and silent to see the end of your Churban, and yearned and desired that you will be an inheritance for the other nations.
Radak: "Shamos" is Makor (like a gerund), with the grammatical form of "ha'Shachach Chanos Kel" (Tehilim 77:10). Sha'of is swallowing, like "Sha'afah Ru'ach" (Yirmeyah 2:24). The Goyim around you, their intent was to make you desolate and swallow you.
Radak citing Targum Yonasan: [Because they aggrandized themselves, and] intended to destroy you all around.
Malbim: Bnei Amon 1 took from Yisrael's inheritance and settled there ? "Madu'a Yarash Malkam Es Gad" (Yirmeyah 49:1), "Al Bik'am Haros ha'Gil'ad Lema'an Harchiv Es Gevulam" (Amos 1:13). They intended to make you desolate and take your land for an inheritance. This is why they sent Yishmael to kill Gedalyah, so Eretz Yisrael would be desolate, and they would take it.
The verses do not specify Amon. They discuss Yisrael's neighbors; verse 5 specifies Edom. (PF)
Why does it say "va'Ta'alu Al Sefas Lashon"?
Rashi: Now in your Churban, everyone speaks about you, saying 'He'ach, they are desolate!'
Radak: Every nation has their special Safah (language) ? "li'Lshonosam? l'Goyeihem" (Bereishis 10:31). They put Yisrael on their Safah, to speak bad about them.
Malbim: They blasphemed Yisrael's Emunah and Kedushah ? "Shamati Cherpas Mo'av v'Gidufei Bnei Amon" (Tzefanyah 2:8).
What is "Dibas Am"?
Rashi: It is slander.
Refer to 36:3:4:2-3.