Why does the Torah need to inform us that Aharon carried out Hashem's command?
Rashi: To teach us that Aharon did not deviate one iota from what Moshe told him. 1
Ramban: To teach us that Aharon undertook to personally light the Menorah 2 throughout his life 3 due to the profound teachings that it contained.
See Sifsei Chachamim.
Ramban and Moshav Zekenim: Even though his sons were eligible to perform it - as the Torah writes in Sh'mos 27:21.
Ramban: Perhaps Aharon took his cue from our Pasuk and Vayikra 24:3, which mention only him and not his sons. (Aharon was intimate with his wife even after becoming Kohen Gadol (Rashi 12:2,4). Even after immersing , he is partially Tamei until the following night! R. Yehudah (Pesachim 77a), holds that Tum'ah is Hutrah [totally permitted] b'Tzibur. Aharon could light b'Tum'ah even if his sons were Tehorim. R. Shimon disagrees. Perhaps he explains that Aharon lit whenever possible. Or, he would have intimacy only towards the end of the day (after Hadlakah; this is permitted in a dark house, or for a Chacham who blocks out the light with his garment ? Shabbos 86a) and immerse during the day, to be totally Tahor the next day. (PF)
