Why does the Torah write "Ki Seitzei Machaneh" and not "Ki Seitzei la'Milchamah - al Oyvecha?"
Sifri: To teach us that when going to fight the enemy, one should go in large groups (and not rely on miracles - Malbim).
"Venishmarta mi'Kol Davar Ra". What are the connotations of "Davar Ra"?
Rashi: It is a Mitzvah to guard oneself against all hazards 1 in time of war ? because 'The Satan only prosecutes in time of danger'. 2
Ramban #1: It refers (not to physical dangers, but) to taking care not to sin, as armies tend to do - by eating all kinds of abominable food, unashamedly robbing and stealing, raping and committing all kinds of abominable acts. 3
Ramban #2: It is a warning against doing anything that is forbidden in the course of battle.
Ramban #3 (citing the Sifri) 4 and Targum Yonasan: It is a warning against committing the three cardinal sins in time of war, Avodah Zarah, Giluy Arayos and Shefichus Damim. 5
Avodah Zarah, 20b: It is a warning against thinking lewd thoughts by day - to avoid having an emission by night (discussed in the following Pasuk). 6
Sifri: We learn from "ve'Lo Yir'eh b'cha Ervas Davar" - in Pasuk 15 that the Torah is referring (not to Isurim concerning Tum'os and Taharos or Ma'asros, but) to Isurim concerning Arayos; and the Torah adds the word "mi'Kol Davar Ra", to incorporate Avodah Zarah and Shefichus Damim and all the sins which caused the Cana'anim to be exiled from the land and which cause the Shechinah to depart, whereas "Davar Ra" incorporates the sin of Lashon ha'Ra (and indecent speech - Ba'al ha'Turim).
Refer to 23:10:5:2.
This seems to be a branch of "Venishmartem Me'od le'Nafshoseichem" in 4:15. See Sifsei Chachamim.
Rashi: Because 'The Satan prosecutes in time of danger'. Rosh ? this implies that this is a command to repent, to deny the Satan reason to prosecute.
See also Ba'al ha'Turim.
Ramban: Sins for which the Cana'anim were exiled from the land and which cause the Shechinah to depart - since the Torah, in Pasuk 15, writes "Ervas Davar." See Ramban. See answer #6.
How will we reconciple the current D'rashah - "she'Lo Yeharher ba'Laylah" - with the D'rashah in Shabbos, 150a, which comments on the Pasuk in Yeshayah, 58:13 "Vedaber Davar" - 'Dibur Asur, Hirhur Mutar'?
Oznayim la'Torah: The current D'rashah relies on the Pasuk "Vehayah Machanecha Kadosh", on which it is based.
Perhaps one can also say that regarding Arayos, Chazal have taught that Hirhur is worse than Dibur, and that consequently, since immoral speech is fobidden it would be illogical to permit Hirhur.
Why does the Torah write "Ki Seitzei Machaneh" and not "Ki Seitzei la'Milchamah - al Oyvecha?"
Sifri: To teach us that, when going to fight the enemy, one should go in large groups (and not rely on miracles - ha'Torah ve'ha'Mitzvah). 1
In keeping with the principle 'Ein Somchin al ha'Neis'.
What are the connotations of "Venishmarta mi'Kol Davar Ra"?
Refer to 23:10:2:1-6.
Ramban #4 (citing the Sifri): "Davar Ra" ('Dibur Ra'). incorporates a warning against speaking (Lashon ha'Ra). 1
Avodah Azorah, 20b: It is a warning against a. gazing at a beautiful woman, even if she is not married or b. at a married woman, even if she is not beautiful, or c. at the colorful clothes of a woman (whom he recognizes ? that are hanging-up to dry) or d. at a pair of donkeys, Chazerim or birds whilst they are mating. 2