It is written Elu, and we pronounce it Elav!
Radak: Also "Alav ba'Shamayim Yar'em" (Shmuel I, 2:10) is like this.
Surely "b'Soch ha'Ir" is Yerushalayim, the place of Beis Hashem, the Heichal and Mizbe'ach. Why does it add "b'Soch Yerushalayim"?
Radak: The city in which I chose to make My name dwell in it, they expelled Me from it via their many sins.
What is the meaning of "v'Hisvisa Tav"?
Rashi: You will mark.
Why will he mark the Tzadikim?
Rashi: It is a sign that destroyers should not strike them. Radak - this is like Dam Pesach in Egypt. However, here was in a prophetic vision. .
What is the significance of the letter Tav?
Radak citing Shabbos 55a #1: It signifies Tichyeh (you will live). A 'Tav' was written in blood on the foreheads of Resha'im - Tamus (you will die).
Radak citing Shabbos 55a #2: Tamah (ceased) Zechus Avos 1 .
Shabbos 55a #3: Tachun Zechus Avos. (Tzadikim will be graced with it.)
Shabbos 55a #4: It is the end (last letter) of Hashem's signature [on the decree]. Hashem's signature is Emes.
Shabbos 55a #5: It signifies [for Tzadikim] that they fulfilled the Torah from Aleph to Tav [and Resha'im transgressed from Aleph to Tav].
Tosfos (55a): It ceased for Resha'im. Maharsha - it ceased for all. Resha'im will die without Zechus Avos, and Tzadikim will live in their own merit.
Who were "ha'Ne'enachim veha'Ne'enakim"?
Radak, Malbim: They were Tzadikim in Yerushalayim who screamed over the abominations done in the city. Ne'enakim is [screaming], like "He'anek Dom" (24:17). The Nif'al conjugation is used because it was done excessively. The same applies to "ha'Nidbarim Becha" (33:30).