When did Yerushalayim remember this?
Rashi: In its exile.
What are "Yemei [Anyah u'Mrudeha]"?
Rav Sadya Gaon, Ibn Ezra, Ri Kara, Rid: In the days of [Anyah u'Mrudeha]. Ibn Ezra - it means [bi'Ymei Anyah
What is "Anyah"?
Rav Sadya Gaon: Its weakness.
Rashi: Its poverty.
Palgei Mayim: Its afflictions.
What is "Merudeha"?
Rav Sadya Gaon: Its lowliness.
Rashi: It is an expression of] pain, like "v'Yaradti Al he'Harim" (Shoftim 11:37), "Arid b'Sichi v'Ahimah" (Tehilim 55:3).
Ibn Ezra: Merudeha is poverty. The Mem is from the root.
R. Avigdor citing Eichah Rabah 1:33: Its rebellion against Hashem.
What are "Kol Machamadeha"?
Rashi: All its good treasured things.
Palgei Mayim: The Torah and its Mitzvos. Even its Chukim were treasured to the entire world - "Rak Am Chacham v'Navon ha'Goy ha'Gadol ha'Zeh", "Amim Har Yikra'u", "v'Ra'u Kol Amei ha'Aretz Ki Shem Hashem Nikra Alecha v'Yar'u Mimeka" (Devarim 4:6, 33:19, 28:10).
What is the meaning of "[Ra'uha Tzarim Sachaku Al] "Mishbateha"?
Rav Sadya Gaon: This is like "Shabaton" (Shemos 16:23).
Rashi: [The afflicters] rejoiced over cessation of its Simchah, festivals, Rosh Chodesh and Shabbos.
Rashi citing Eichah Rabah: In exile, Yisrael rested on Shabbos, Yom Tov and in Shevi'is. The nations taunted them 'fools! In your land you did not cease - now in exile, you cease?!' In your land you did not guard [Shabbos] - now in exile, you guard 1 ?!'
Ibn Ezra: [The enemy] laughed at Yisrael's ceasing from action - there is nothing for them to do!
Ri Kara: Afflicters who saw her in her days of grandeur, when they saw her now in her disgrace, they laughed at the precious matters that ceased from her. Mishbateha it is an expression of ceasing. This is like "va'Yishbos ha'Man mi'Macharas" (Yehoshua 8:12; the Targum is u'Fasak Mana) and "Yom va'Laylah Lo Yishbosu" (Bereishis 8:22).
Rid: It is the Bitul of her honor and grandeur.
Palgei Mayim: Now that the nation fell to its oppressors, and no one helps it, they [did not honor the Mitzvos; they] mocked even Mitzvos of Sechel that are not Chukim, e.g. Shabbos and Mo'adim.
The Buber edition of the Midrash explicitly says that they taunted them also for guarding Shabbos. Shabbos is obligatory in Chutz la'Aretz just like in Eretz Yisrael! Perhaps this is like Ramban (Vayikra 18:25, based on Sifri Ekev 43), that the Mitzvos are primarily for Eretz Yisrael. Most apply in Chutz la'Aretz, so we will be used to them when we return to Eretz Yisrael. Why did they guard Shevi'is in Bavel? It is not obligatory even mid'Rabanan (Yadayim 4:3)! Perhaps they were stringent to atone for their prior sin. (PF)