What is the significance of the word "Re'u"?
B'rachos, 55a: This teaches us that, before appointing a communal leader one should obtain the people's consent. 1
Da'as Zekenim and Rosh: When Moshe said that Betzalel would build the Mishkan, Yisrael murmured, and accused him of taking all the greatness for himself and his family; to which Moshe said 'Re'u ... "See that I am only doing what Hashem commanded'. 2
B'rachos, 55a: When Hashem asked Moshe whether Betzal'el foind favor in his eyes and he replied 'If You consider him worthy, how much more so I!', to which Hashem responded 'Nevertheless, go and inform Yisrael!' See Torah Temimah, note 22.
Da'as Zekenim and Rosh: Similarly, initially Moshe thought that he himself would build the Mishkan, and Hashem disillusioned him and said "Re'u Kara Hashem be'Shem Betzalel ... " - See that I have appointed Betzalel, grandson of the Tzadik, Chur, who was killed [for protesting] in the episode of the Eigel, to build the Mishkan to atone for the sin of the Eigel.
Who was Chur?
Rashi: He was the son of Miriam. 1
See Sifsei Chachamim. The question arises as to why Rashi did not tell us this in Sh'mos 31:2? Refer also to 35:30:1:2*.