1)
Why does it say "Eich Nashir"?
1.
Pesikta Rabasi (31), Shocher Tov: They put their hands in their mouths and mutilated them. They told their captors that the fetters cut off their fingers.
2.
Malbim: We can sing for you songs of physical success that we sang in Tziyon, for also here we have success. However, Shir Hashem of Kodesh that we used to sing in Yerushalayim for the Shechinah there, Ru'ach ha'Kodesh and Nevu'ah, Torah, Avodah and the miracles - this Divine song, how can we sing it in a foreign land that is not prepared for these spiritual Segulos?!
2)
What is "Admas Nechar"?
1.
Radak: It is Admas El Nechar (land of a foreign god), the antithesis of Shir Hashem.
