1)
What is the meaning of "ha'Charev Nechervu"?
1.
Radak: They were killed via swords.
2.
Malbim: They fought each other with swords.
2)
What is the significance of their mistake?
1.
Radak (24): They were confident that they need not fight; they did not come like those who must fight. (Therefore, Yisrael defeated them.)
