What is the meaning of "Ken Yazeh Goyim Rabim"?
Rashi: So now, [Yakov's] hand will overpower, and he will cast the horns of the Nochrim that scattered him.
Radak: Yazeh refers to speech. This is like Yatif, which refers to sprinkling and speech. "Natfu Mayim" (Shoftim 5:4) is sprinkling, "Al Tatifu Yatifun" (Michah 2:6). Here, Yazeh is an expression of speech - it is Po'el Yotzei l'Shelishi (makes a second party acts on a third). Just like they are astounded at Yisrael's lowliness, they will be astounded at their grandeur, and talk about them constantly.
Malbim: Just like [Yakov] was deformed from human form - the ultimate lowliness, so his strength to expel many nations will be the ultimate strength.
Why will they close their mouths?
Rashi: It will be amidst great astonishment, for they saw in them honor not seen in any person.
Radak: Even kings will see that their honor is great - "v'Ra'u Goyim Tzidkech v'Chol Melachim Kevodech" (62:2). Yipetzu is to open [their mouths], like "Mekapetz Al ha'Geva'os" (Shir ha'Shirim 2:8); he opens his steps, and jumps. They will open their mouths to tell My greatness. Or, it can mean closing - they will close their mouths amidst astonishment.
Malbim: Normally, when one expels Nochrim, their kings contest for them. They will close their mouths and be silent.
What is the meaning of "Asher Lo Supar Lahem Ra'u va'Asher Lo Sham'u Hisbonenu"?
Radak: They will see more of His grandeur than was told to them; more than they heard, they will contemplate His grandeur.
Malbim: They are two aspects of impossibility. (a) It cannot be carried out in deed. (b) It cannot be in thought. The latter is when there is a contradiction, e.g. a square circle. What cannot be in deed, one can think about it. There is no contradiction between flying and a man. The salvation of Yisrael, until now it was impossible in deed. Nothing like this occurred - what was not told to them, they will see. They could not even fathom it
What is the meaning of "Hisbonenu"?