The Chabad translation of Mishneh Torah includes an editor's note to Hilchot Avodat Kochavim 4 saying:
There is a unique dimension to the laws of an עיר הנדחת that is not found in regard to any of the other prohibitions of the Torah. In this context, the city is considered as a single entity and the inhabitants and their property are not considered as individuals but as members of this wicked collective (Tzaphnat Pane'ach, Likkutei Sichot, Vol. 9).
Can anyone help point me towards where I can read the relevant passage in these two sources? Many thanks.