וְקָרַבְתָּ֗ מ֚וּל בְּנֵ֣י עַמּ֔וֹן אַל־תְּצֻרֵ֖ם וְאַל־תִּתְגָּ֣ר בָּ֑ם כִּ֣י לֹֽא־אֶ֠תֵּן מֵאֶ֨רֶץ בְּנֵי־עַמּ֤וֹן לְךָ֙ יְרֻשָּׁ֔ה כִּ֥י לִבְנֵי־ל֖וֹט נְתַתִּ֥יהָ יְרֻשָּֽׁה׃
tu vas arriver en face des enfants d’Ammon. Ne les attaque pas, ne les provoque point: je ne te permets aucune conquête sur le sol des enfants d’Ammon, car c’est aux descendants de Loth que je l’ai donné en héritage.
Chizkuni
וקרבת מול בני עמון, “when you come near to being opposite the Bney Ammon;” actually they did not get to the boundary of the Bney Ammon, as their lands were to the east of both the kingdoms of Sichon and Og, king of Bashan.
Ibn Ezra
You will come toward the Children of Ammon i.e., when you will come toward them.
Kli Yakar
Do not harass them or provoke them. It does not say here “do not provoke them to war” as it says above regarding Moab, because mere provocation without war was not forbidden regarding Moab, but for Ammon even simple provocation without war was forbidden. This is because Moab hired Balaam against Israel, and we do not find that Ammon had any part in this. Even though his actions did not succeed, nevertheless it caused distress to Israel. Furthermore, Moab also had a part in the sexual immorality, and we do not find this among the children of Ammon, even though by not greeting them with bread and water they did cause them to engage in immorality as explained above in Parashat Pinchas (Numbers 25:17). Nevertheless, we do not find that they made their daughters promiscuous. Perhaps this traces back to their roots, because even in the incident with Lot’s daughters, their mother was somewhat modest.