What is the Torah referring to when it writes that Moshe, Aharon and Adas Bnei Yisrael did all that Hashem commanded them?
Rashi: Moshe stood them, Aharon waved them 1 and Yisrael leaned their hands on them.
Seforno: Between them they helped the Leviyim to do everything that needed to be done regarding shaving, washing their clothes and bringing their Korban.
Moshav Zekenim, citing R. Eliezer of Garmaiza: The Leviyim did not want to shave themselves. All Yisrael helped and shaved them Bal Korcham (against their will).
Why does the Pasuk repeat "Kein Asu lahem Bnei Yisrael"?
Seforno: To inform us that Yisrael made an effort to do for the Leviyim whatever needed to be done, in order to carry out the Will of Hashem.