Why does the Torah place this Parshah here?
Rashi #1: Because when Hakadosh-Baruch-Hu told Moshe to give the B'nos Tz'lofchad their portion of inheritance, he thought that Hashem was instructing him personally to do so, which in turn, implied that He (Hashem) had cancelled the decree prohibiting him from entering Eretz Yisrael. So Hashem informed him that the decree was still in place.
Rashi #2: Moshe thought that the decree that he not enter Eretz Yisrael had been cancelled 1 , since he had entered the portion of B'nei Gad and B'nei Re'uven. 2
Ramban: To inform Moshe that although Hashem had told him earlier "la'Eileh Techalek ha'Aretz ... ", it would not be done through him. 3
Rashi: It can be compared to a king who forbade his son to enter the throne-room. When he entered the outer gate, the son followed him; the hall, the son followed him. But when the son attempted to enter the throne-room, the king told him that from now on, he was forbidden to proceed.
Why does the Parshah appear here and not at the end of Chukas? - See Sifsei Chachamim.
See 26:53.
Why did Moshe not carry out Hashem's instructions immediately?