What is the significance of the fact that they encamped "opposite Ba'al Pe'or"?
Rashi: Moshe is referring to the sin of Ba'al Pe'or, to point out to the people that, although his sin was not forgiven, their's was 1 (and they would enter Eretz Yisrael) - provided they obey Hashem's Mitzvos, as the Pasuk goes on to state.
Ramban: Refer to 4:5:1:1 and note.
Targum Yonasan: The Torah is informing us that, they encamped in the valley 'weeping' on the sin of Ba'al Pe'or - a sign that they they had done Teshuvah - and that consequently, provided they adhere to the Chukim and Mishpatim that Hashem commands them, they will be allowed to enter and inherit Eretz Yisrael. 2
Oznayim la'Torah: This was the location where Moshe would be buried, and the moment he heard that he would not cross the Yarden and that he would die and be buried there, he remained there as a consytant reminder of his day of death in order to do Teshuvah. 3
How will we reconcile this Pasuk with the Halachah that prohibits mentioning an Avodah Zarah as a landmark?
Oznayim la'Torah: Since it is mentioned in connection with Teshuvh - refer to 3:29:1:3 and note - it is permitted.
