Malbim: He arranges his three Nevu'os. The first is about Ya'ar ha'Negev, i.e. Eretz Yisrael in general. Radak (7) - verse 8 explains, this is Admas Yisrael.

Radak: This is lighting and burning, like "va'Yatzes Esh b'Tziyon" (Eichah 4:11).

Radak citing Targum Yonasan (version #1): I will incite against you a nation powerful like fire.

Radak citing Targum Yonasan (version #2): I will light a fire in you.

Radak (7): Verse 8 explains, I will remove My sword from its scabbard. Malbim (8) ? the sword will consume people like a fire consumes a forest.

Malbim: He will totally burn the entire forest at once with a big fire.

Rashi (8), Radak: This is a Mashal for Tzadikim and Resha'im, like verse 8 explains.

Radak citing Targum Yonasan: [The nation will kill among you] rich and poor.

Malbim: First it will consume the moist, and afterwards the dry; nothing stops the fire. If it would consume the dry first, the moist would stop the fire from spreading.

Radak: The matter is repeated in different words to strengthen it. The fire will not extinguish. The flame will keep increasing until all are consumed ? both Galus and Cherev.

Rashi: This is like "Tzareves ha'Shechin" (Vayikra 13:23), an expression of a burn.

Radak #1: Those who will not die, their faces will burn from shame in their Galus. Kol Panim is the faces of all the Golim.

Radak #2: This refers to other nations, like it says "v'Hotzeisi Charbi mi'Tarah" (8).

Rashi: All the people in the south of Bavel.

Radak #1: [The faces of the Golim will be shamed] from Yerushalayim in the south, to Bavel in the north.

Radak #2: This is like mi'Negev l'Tzafon. Just like Yisrael were stricken from south to north, so the other nations will be stricken and exiled, like them.

Malbim: The fire began to consume in the south; it will spread to the north.