What is the meaning of "Yimotu Aleihem Gechalim"?
Rashi: Coals of Gehinom should fall on them. They should lie in them until they totter and extinguish by themselves. It turns out that the body perishes.
Radak: Coals from Shamayim, i.e. Hashem's anger, should lean on them.
Seforno: The coals of the slander should be reversed onto them.
Malbim: Coals should fall on their lips.
What is the meaning of "ba'Esh Yapilem"?
Rashi: The one who takes vengeance will make him fall.
Radak: The sin of their lips should make them fall.
Malbim: They themselves will fall in pits of fire from which they cannot rise.
What are "b'Mahamoros"?
Rashi: It is with wars and scuffles. This is like "Mamrim Heyisem" (Devarim 9:7).
Radak: They are deep pits from which they will not rise. The Yerushalmi (Mo'ed Katan 1:5) says that initially they buried them in pits. After the flesh was consumed, they gather the bones and bury them in coffins.
