Why does the Torah write here "Al Tisgar bam Milchamah", and by the B'nei Amon (in Pasuk 19) only "Al Tisgar bam"?
Rashi: Because here Hashem only forbade fighting Mo'av, but not harassing them, 1 whereas regarding Amon, even harassing them was strictly forbidden.
Bava Kama, 38b: Because here Hashem only forbade fighting Mo'av, but not rendering them subservient by making them bring them water and food, 2 whereas regarding Amon, even that was strictly forbidden.
Rashi: And they did in fact, harass them a. by appearing before them armed and scaring them and b. by actually robbing them and taking spoil - which explains why Mo'av was afraid of them - See Bamidbar 22:3.
See Torah Temimah, note 5.
Why were Yisrael allowed to harass Mo'av but not Amon?
Rashi: Becaue of the modesty of Amon's mother - the younger daughter of Lot - who did not publicize the fact that her son Amon was born from her father like her sister did - by calling her son 'Mo'av', implying 'me'Av'.
What was "Ar"?
Why did Hashem not order Moshe to take revenge aganst Mo'av, like He did with regard to Midyan?
Refer to Bamidbar, 31:2:2:1-4
What are the ramifications of "ki li'Venei Lot Nasati es Or Yerushah"?
It is the source for the Halachah that a Nochri inherits his father. 1
See also Torah Temimah, note 6.
Why would Moshe have thought to fight Mo'av without permission, that Hashem needed to forbid it?
Bava Kama 38a: He thought that, since Hashem ordered him to take revenge against Midyan, all the more so would he need to take revenge against Mo'av for causing them to sin with their daughters. 1
Moshav Zekenim (in Chukas Bamidbar, 22:2): Why did Hashem need to forbid fighting Edom and Amon? For them He needed to forbid even mere aggression.
Since the Torah forbade fighting Mo'av, why, in Melachim 2, 3:18 & 19, did Elisha issue a command to fight them?
Moshav Zekenim (in Ki Seitzei, Devarim, 20:19): Because Elisha's command pertained exclusively to the section of Mo'av that Sichon had conquered, which became permitted to Yisrael. 1
As the Gemara states in Gitin 38a.
QUESTIONS ON RASHI
Rashi writes that Hashem forbade only fighting Mo'av; Yisrael appeared armed in front of them and took spoils, and therefore Mo'av was afraid of them. - Hashem forbade fighting them before the episode with Midyan. But the Gemara in Bava Kama 38a explains that Hashem only forbade this after He said to take revenge against Midyan, and Moshe thought that all the more so against Mo'av?
Refer to Bamidbar 22:3:151:1 & 2 and note.
