Bearing in mind the Pasuk in Vayikra (8:7 - 13), which indicates that Moshe first dressed Aharon the belt and then his sons, why does the Torah here write "ve'Chagarta osam Avneit, Aharon u'Vanav", implying that he girded them all the belt, one after the other?
Ramban: The Torah incorporates Aharon with his children because it did not mention the belt earlier in Pesukim 5 & 6. 1
Rashbam #1: This gives rise to the Machlokes as to whether the belt of the Kohen Hedyot contained Sha'atnez, like that of the Kohen Gadol, or not. 2
Rashbam #2: According to the simple P'shat, this is the way the Torah speaks, and one need not take the change too seriously.
Yoma, 6a: In fact, Moshe first dressed Aharon, and the Torah writes here " ... osam Avneit, Aharon u'Vanav" to teach us that the Avneit of the Kohen Hedyot was similar as that of the Kohen Gadol (and contained Sha'atnez). 3
Precisely because Aharon wore a belt just like they did. The Torah mentioned the Mitznefes however, because it differed from the Migba'os that his sons wore (Ramban - Refer to 28:4:4:2). The question arises however, why the Torah mentioned the Kutones by Aharon (See Pasuk 5) - seeing as he wore the same tunic as his sons?
See Yoma 5b & 6a). Refer also to 28:39: 1:1 & 29:35:1.1:1. See also Ramban, Pikudei, Sh'mos 39:29.
See Torah Temimah, note 12.
Why does the Torah not mention the Michnasayim here?
Ramban (above, in 28:3): Because it mentioned earlier 1 that a Kohen who performs the Avodah without the Michnasayim is Chayav Misah, it is obvious that they will wear them and it is unnecessary to repeat them here. Moreover, the Torah separates them from the other Begadim because, whereas Moshe dressed them in the other Begadim, 2 the Michnasayim, which were to cover their Makom Ervah, they put them on themselves due to Tzeni'us. 3
Why does the Torah insert here the phrase "Vehaysah lahem Kehunah ... "?
Zevachim, 17b: It inserts it after the Bigdei Kehunah to teach us that when the Kohanim are not wearing the Bigdei Kehunah, they are not considered Kohanim, and are Chayav Misah like Zarim 1 if they perform the Avodah. 2
Why does the Torah add "le'Chukas Olam"?
Zevachim, 18a: To teach us, via a Gezeirah Shavah "Chukas Olam" "Chukas Olam" from Shesuyei Yayin, in Shemini, Vayikra, 10:9 that if a Kohen performs the Avodah not wearing his four Begadim (or the Kohen Gadol his eight), his Avodah is Pasul. 1
What is "Umileisa Yad Aharon ve'Yad Banav" referring to?