Why does it say "Shenis"?
Radak: Both visions hint to the same matter, even though what he saw changed 1 . This is the second time Hashem asked him what he sees, and he answered. It is not coming to teach how many times he saw, for it mentions only this. This is like "va'Yhi Devar Hashem El Yonah Shenis" (Yonah 3:1), for he spoke with him twice about Ninveh. This is unlike the Midrash that expounds that he spoke with him twice, but not a third time.
Malbim: The first time, Hashem informed him when the evil will come. Now He informs him from where it will come.
What is "Sir Nafu'ach"?
Rashi: It is a boiling pot. Radak - Nafu'ach is an adjective. It gives off hot air (steam) when it is boiling, just like one who blows at a fire exudes hot air from his mouth at the time he blows.
Radak citing Targum Yonasan: It is a king boiling like a pot.
What is "Panav"?
Rashi: It is its (Malbim - the side that) bubbles.
Radak: It is the side from which they pour.
Radak citing his father: It is the supports, or oven, on which they rest the pot.
Radak citing Targum Yonasan: It is the Degel 1 of its encampment.
Recall that Targum Yonasan explains that "Sir' is a king. (PF)
Why does it say "Mipnei Tzafonah"? It should say El Pnei Tzafonah!
Radak: Pnei Tzafonah implies that the face (the side from which they pour) faces the north. The prefix Mem teaches that those who made it hot were from the north, i.e. Bavel, which is northeast of Eretz Yisrael.
Radak citing his father: Since the supports from (i.e. between) which they bring the fire faced north, this shows that the one who lights the fire under the pot will come from the north.
Radak citing Targum Yonasan: The camp is coming from the north.
Malbim: People will flee the enemy [from the north] and try to escape from the other side (but it will not help. Bavel will catch them and exile them to Bavel.)
QUESTIONS ON RASHI
Rashi writes that "Sir Nafu'ach" is a boiling pot. What is the significance of this?
Radak, Malbim: The pot represents Yerushalayim, just like in Yechezkel (24:3) "Shefos ha'Sir Shefos." Malbim - the people inside are compared to meat. Just like a pot saves the meat from the fire, lest it burn it, so the city and fortresses save from the enemy. A pot bubbles when it is on a big fire and uncovered. This is a metaphor for fire of the enemy that exceeds the strength of the pot. The protection around does not help when it is exposed above - "Haser Mesukaso v'Hayah Leva'er" (Yeshayah 5:5). Via this, the wall falls and it is trampled.
