Why will you not have sudden fear?
Malbim: This is due to Bitachon. R. Yonah (26) - Bitachon is from the root of Emunah - "Betach ba'Shem va'Ase Tov Shechan Eretz u'Re'e Emunah" (Tehilim 37:3). Bitachon is clear, strong Emunah, in the heart, of Hashem's salvation. He truly relies on Him - "v'He'emin ba'Shem 1 " (Bereishis 15:6), "v'Nish'an Al Hashem Kedosh Yisrael be'Emes" (Yeshayah 10:20). Also refer to 3:7:1:3*.
R. Yonah: Bitachon includes belief in everything that Hashem promised via His Nevi'im and angels - "Yavesh Chatzir Navel Tzitz u'Devar Elokeinu Yakum l'Olam" (Yeshayah 40:8). (Is one who hears from an angel not a Navi? Ralbag (Shoftim 13:16) - it is not the way of Nevu'ah for two to hear together from an angel. - PF)
What is "Sho'as Resha'im"?
Rashi: Destruction that comes on Resha'im. R. Yonah - even if destruction was decreed to come on Resha'im in that place, you will be saved 1 and not perish in the city's sin 2 , since you are clean from sin and guard Torah.
Malbim: Via Hashem's Hashgachah.
R. Yonah (26): Also in Nachum (1:7-8) it says "Tov Hashem l'Ma'oz b'Yom Tzarah v'Yode'a Chosei Vo; uv'Shetef Over Kalah Ya'aseh Mekomah." Hashem will make a place proper for them. Those who hope to Him will not be captured at a time of affliction, even if eradication was decreed on the place.
