Why does it say "Ein Ayef v'Ein Koshel Bo"?
Rashi: [The enemy] will not tire or stumble in His running. [Hashem will cause this,] to fulfill "Yemaher Yachishah" (19) that they say in front of Him.
Radak: This is an exaggeration. It shows their great desire and speed to come. No one will bang his foot on a rock amidst running.
Malbim: Nothing will delay their speedy arrival. Ayef is tiring by oneself; Koshel is an external hindrance.
Why does it say "Lo Yanum v'Lo Yishan"?
Radak: They will not sleep at all during the day, and even at night, not one of them will have a fixed sleep (refer to 5:27:4:2).
Malbim: Yanum is tiring due to exertion. Yishan is the normal need to sleep at night. Therefore, they will be able to go day and night.
What is the meaning of "Niftach"?
Rashi: It is an expression of untying, like "va'Yfatach Es ha'Gemalim" (Bereishis 24:32).
What is the significance of no belt opening and no shoelace snapping?
Rashi: They will not see any sign of stumbling to fear Me and not come.
Radak: They will not untie their belts or shoelaces to have a fixed sleep (refer to 5:27:2:1). Rather, at night they will doze with their clothes and shoes on. This is an exaggeration. "Nitak" is untying the knot of the shoe.
Malbim: They will not have even a small delay due to these. It is common for laces to snap when going a long way. One can go without laces - even so, they will not need to.
