Bearing in mind that this Parshah was said on Rosh Chodesh, and the Korban Pesach was only brought later, how can the Torah write that Yisrael carried out what Moshe and Aharon told them?
Rashi: Since Yisrael undertook to bring the Pesach, the Torah reckons as if they had already brought it.
Why does the Torah use the (otherwise superfluous) word "va'Yelechu va'Ya'asu"?
Rashi: To teach us that they received reward for going to perform the Mitzvah, as well as for the actual performance itself. 1
What is the significance of the phrase, "Ka'asher Tzivah Hashem Es Moshe v'Aharon"?
Rashi and Ramban (citing the Midrash): It teaches us that they performed what Moshe and Aharon told them, down to the last detail. 1
Gur Aryeh: Why was this so significant? The Bnei Yisrael had to slaughter the Egyptian gods, which (under natural terms) would have put them in great danger (see 8:22). Nevertheless, the Bnei Yisrael trusted in Hashem, and fearlessly carried out the Korban Pesach with all of its details.
Why does the Torah add the words "Kein Asu"?
Rashi and Ramban #1 (citing the Midrash): It refers to Moshe and Aharon, who also did like they commanded Yisrael. 1
Ramban #2: It is the way of the Torah to repeat that they did it, 2 to teach us that they performed what they had been told to perfection.
Ba'al ha'Turim: One Asiyah refers to the Pesach, and the other, to Milah.
Oznayim la'Torah: To teach us that Yisrael did what Moshe and Aharon told them, not for the reason that Moshe and Aharon gave (that it would hasten the Redemption and protect them, but) because they instructed them to.
But of course they did! See 12:28:151.
See for example Shemos 39:43 (Ramban), and refer to Bereishis 6:22:1:2.
QUESTIONS ON RASHI
Rashi writes: "'The Bnei Yisrael went, and did' - Had they done [the Korban Pesach] already?" In what way was that implied?
Gur Aryeh: "They went and did" makes it sound like immediately after they went, they carried it out. (Rather, Rashi explains, because they immediately accepted to do the Mitzvah, it is considered as if they had already done so.)
Rashi writes: "Rather, once they accepted upon themselves [to offer the Korban Pesach], the verse considers it as if they had already done so." Why does Hashem consider a positive intention, as if it was already put into action?
Maharal (Chidushei Agados Vol. 2, p. 141, to Kidushin 39b): It is fitting that those good intentions come to pass; and Chazal teach that "one who wishes to purify himself, they assist him [from Heaven]" (see Yoma 38b). 1
Maharal (loc. cit.): Whereas an intention to do evil is not considered as if already carried out, because it is not fitting to be; and from Heaven they do not assist him to do so (although they do provide an opening - Yoma 38b).
Rashi writes: "'They went, and they did' - The text enumerates even the walking [towards the performance of the Mitzvah], to give reward for the walking [in addition] to the reward for doing." What indicates this in the text?
Gur Aryeh: The idea of this verse is that they immediately accepted to do the Mitzvah, and Hashem considered it that they had already done so (Rashi). But to convey this, the Pasuk could have said only 'va'Yeitze'u va'Ya'asu.' 1 The choice of term "va'Yelechu" (they went) adds reward for the walking.
For example, as in Shemos 35:20.
Rashi writes: "... To give reward even for the walking." What is the significance of walking towards a Mitzvah?
Maharal (Derech Chayim p. 197, to Avos 4:17): Though good deeds, a person rises above this physical world, towards belonging to Hashem. Specifically, in concept, moving towards an objective means becoming one with it. 1 Walking towards a Mitzvah means becoming one with Hashem.
Maharal (loc. cit.): The Gemara says, "Rabbi Yosi said, 'May my portion be among those who perish on the way to a Mitzvah" (Shabbos 118b). Maharal - In a way, this is even more advantageous than having already done and acquired the Mitzvah, for such a person passes away while attaching himself to Hashem. (Perhaps the advantage is in his yearning to fulfill the Mitzvah - EK). Also see Maharal (Chidushei Agados Vol. 1, p. 58, to Shabbos 118b), as to why this applies specifically to someone who was still travelling on the way to that Mitzvah. Yet, we find various approaches to this in Maharal. See Nesivos Olam (Nesiv ha'Avodah Ch. 5, p. 89) - This concept applies specifically to walking to the Beis ha'Keneses -- for Hashem is there. When one is far away, and yet moves ever closer despite that distance, it is true Deveikus (attachment). Maharal (Derech Chayim p. 253, to Avos 5:14) - The same is true of walking to the Beis ha'Midrash (as that Mishnah teaches, there is some reward even for those who come, but do not learn). Maharal explains - Torah learning requires direct transmission from teacher to student, such that walking to the Beis Midrash is a prerequisite for learning -- which is not necessarily the case of other Mitzvos. To summarize, Maharal speaks of three levels in Sechar Halichah - a) walking to the Beis ha'Keneses; b) to the Beis ha'Midrash; c) towards other Mitzvos. As for our Pasuk, perhaps walking to bring a Korban is the same as walking to Tefilah, which is called Avodah. (EK).
Rashi writes that also Moshe and Aharon did [like they commanded Yisrael]. Of course they brought the Korban Pesach! Why would this be surprising?
Riva (citing R. Elyakim): One might have thought that Moshe and Aharon were exempt from bringing the Korban Pesach, bearing in mind that the tribe of Levi was not enslaved, and did not therefore require this merit to be redeemed. 1
Da'as Chasam Sofer (Avodas Hashem 10): First Yisrael did, and then Moshe and Aharon - to teach us that when going to do a Mitzvah, one does not honor Gedolim to let them go first; but whoever is zealous to do it first gains. 2
Gur Aryeh (citing Mizrachi): I might have thought that only the Bnei Yisrael, who needed to be redeemed, required the Korban Pesach to merit it; whereas Moshe and Aharon, who were themselves redeemers (as Hashem's messengers), had no need for the Korban! Rather, we see that Moshe and Aharon were redeemed as well.
