What is "Kol Se'on So'en b'Ra'ash"?
Rashi (from Sotah 8b): Is an expression of a Se'ah 1 (measure).
Rashi: There is no similar word in Tanach. Based on context, it is exultant screaming of victory in war - horses beating their hooves, and clanging shields.
Radak: It is the noise of horses in war, like "b'Ra'ash v'Rogez Yegame Aretz" (Iyov 39:24), and of spears - "l'Ra'ash Kidon" (ibid., 41:21). The Nun is from the root; Se'on is To'ar (kind of person) (a kind of noise), and So'en is a verb. All who make war, they fight noisily. Alternatively, Se'on refers to war.
Malbim: The verse personifies Se'on, as if it groans over itself. The Nimshal is many nations; they destroyed themselves via their clamor.
What is the significance of "Simlah Megolalah v'Damim"?
Rashi: Normally, one hears the clamor of victors in war, and the clothes of the killed are bloody. There was no noise or blood in this war!
Malbim: It is a red garment that they raise on a pole, for a sign to spill blood without mercy. It is dirty with blood that it spilled.
Why does it say "v'Haysah li'Sreifah Ma'acholes Esh"?
Radak: The angel struck [Machaneh Ashur] at night, and they were burned (Melachim II, 19:35). Some say that the Neshamah was burned and the body survived, and some say that also the body was burned, but not the clothes (Shabbos 113b).
Malbim: The knife of fire, it itself was burned. The enemy that fed everyone, burned itself. Death killed itself. Man did not overpower the enemy - it caused its own destruction via Hashem's angel.
