Why did Hashem state His rebuke in the plural, including Moshe among the rebels?
Rashi #1: In keeping with the saying, 'The cabbage is smitten together with the weeds.' Sometimes the innocent are smitten together with the guilty. 1
Rashi #2 (to 16:22): Because Moshe was partly to blame, 2 for failing to pass on the prohibition to collect the Manna on Shabbos.
Seforno: Because he was partly to blame, inasmuch as he only told them to collect on six days and not seven, without explaining to them why. 3
See Sifsei Chachamim; see also Torah Temimah citing Sanhedrin 11a, and in note 42.
Which explains why they did not believe him when he informed them that the Manna would not fall on Shabbos. They would have taken him more seriously had he taught them the reason behind the prohibition - that collecting it (picking from where it was connected to the ground) and carrying from one domain to the other, are intrinsically forbidden on Shabbos.
QUESTIONS ON RASHI
Rashi writes: "'How long shall you (pl.) refuse' - This is a popular parable; 'Along with the thorns, the cabbage also gets cut down.' [In other words,] due to the wicked, the virtuous are [also] disparaged." In our context, this would mean that although Moshe himself had not sinned, Hashem included Moshe in His rebuke. Yet Rashi wrote above (to 16:22), that Moshe had in fact erred - by failing to tell Bnei Yisrael about the Shabbos, until they were surprised to gather a double portion on the morning of Yom Shishi!
Gur Aryeh: Moshe's omission was not so severe, as to be termed "refusal to observe Hashem's Mitzvos." Had Moshe not erred, he would not have been included in the rebuke at all. Rather, Moshe is included under the heading of this harsh rebuke - along with the members of the nation who did fail in their observance of the Mitzvos - only because he himself did sin in some way.
Rashi writes: "Due to the wicked, the virtuous are [also] disparaged." Why does Hashem's justice work this way?
Maharal (Chidushei Agados Vol. 3, p. 13, to Bava Kama 92a): The whole of humanity is viewed one collective unit. Each person has two aspects - himself as an individual, and as a member of the community. Although Moshe Rabeinu, as an individual, was of course on a level above and apart from everyone else, yet the Torah was not given to individuals - but rather to the people as a whole. As such, Hashem said to everyone collectively, "How long will you refuse to observe My Torah!" 1
This might not line up with Maharal's approach here in Gur Aryeh, see the preceding question. Also see Maharal in Nesivos Olam (Nesiv ha'Zerizus Ch. 2, p. 187) - Chazal write that when Bnei Yisrael sinned with the women of Moav, Moshe 'threw up his hands' and could not react (see Rashi to Bamidbar 25:6). Maharal explains that Moshe, as (effectively) king over Yisrael, was part and parcel of the nation - as we learn from the collective rebuke in our Pasuk - and therefore when they sinned, he found himself powerless to combat them (until Pinchas came). This Maharal as well, illustrates how Moshe was automatically associated with the deeds if the nation - and not due to any shortcoming on his part.
