What is the meaning of "ha'Lo Shamata leme'Rachok"?
Rashi: Why do you aggrandize yourself? It is not due to you! You heard from afar 1 via Nevi'im that I decreed to bring you against these nations - "Hoy Ashur Shevet Api" (Yeshayah 10:5)! Radak - it says [about pride like yours] "ha'Yispa'er ha'Garzen Al ha'Chotzev Bo" (ibid., 10:15).
Malbim (Yeshayah 37:26): Had you heard the Nevu'ah from afar, where you live, you would know that I did (conquered these nations), and not your strength!
What is "lemi'Ymei Kedem"?
Rashi (from Pesachim 54a): From when the world was created, there was such an intent - "Ki Aruch me'Esmol Tafteh Gam Hu la'Melech Huchan" (Yeshayah 30:33). This refers to Sancheriv, who was burned in the fire of Gehinom - "Ne'um Hashem Asher Ohr Lo b'Tziyon" (ibid., 31:9).
Radak citing his father: ["Osah Asisi" - I made Yerushalayim] from of yore, "vi'Ytzrtiha" - this is like "v'Yotzrah me'Rachok Lo Re'isem" (Yeshayah 22:11).
Malbim (Yeshayah 37:26): Nevi'im prophesized this a long time ago.
What did Hashem bring?
Rashi: The strength in your hand.
Radak citing his father: Did I bring you against Yerushalayim to make it desolate, and its residents powerless?!
Malbim (Yeshayah 37:26): [He planned] the destruction of these place [from before, and brought it].
What is the meaning of "u'S'hi Lahshos"?
Rashi: This was My decree, that you will make fortified cities desolate, mounds of earth in which vegetables grow.
Refer to 19:25:3:2.
What is the grammatical form of "Lahshos"?
Radak: The root is Sha'ah. [The infinitive] should be Lehash'os, like in (Yeshayah 37:26). Because the Aleph is omitted here, the Nekudos under the Lamed and Hei changed.
What are "Galim Nitzim"?
Radak: It is desolate, like "Arich Titzenah" (Yirmeyah 4:7). Ba'al ha'Turim - Nitzim appears three places in Tanach. Here, and this same verse in Yeshayah (37:26), and in Shemos 2:13 "Ivrim Nitzim" (Dasan and Aviram). This teaches that Resha'im will be desolate - "Ki Mesu Kol ha'Anashim ha'Mevakshim Es Nafshecha" (Shemos 4:19). Chazal expounded that they lost their property (Nedarim 64b); and their houses were destroyed (the land swallowed their entire families in Korach's rebellion).
Malbim (Yeshayah 37:26): You made the cities desolate mounds - from them will sprout fortified cities. This is like a planted seed, which decays, and produces a tree. So the cities destroyed will be rebuilt stronger and better than initially!