What is the meaning of "Karsu Yarah"?
Rashi: They have strength to cut the entire forest.
Radak #1: Some say that this is a command, like "Charvu Me'od" (2:12). It is as if it addresses the army.
Radak #2: Some say that Karsu is past tense 1 , like Shamru and Zachru. "Yarah" is the trees of the forest. This is a metaphor for Egypt, or its great officers. Yonason translates 'its great ones.'
Radak: Some disagree, for "Ne'um Hashem" is never used with the past tense. They forgot "Yardu la'Tavach Ne'um ha'Melech Hashem" (48:15) and in the rebuke, "Kulchem Peshatem Bi Ne'um Hashem" (2:29). The past is used in place of the future. This often happens in Nevu'ah, for Nevu'ah for the future exists, as if [already] came.
What cannot be investigated?
Rashi: The number of their (Radak Nebuchadnetzar's) soldiers.
Malbim: The number of trees in the forest (population of Egypt). Even so, the choppers cut all of it, for they were innumerable.
