Why does the Torah need to insert the (otherwise superfluous) phrase "be'Hakrivam Eish Zarah ? "?
Seforno: To teach us that this was their only sin.
Why does the Torah need to add "u'Banim Lo Hayu lahem"?
Seforno and Riva (in Pasuk 3, citing Midrash Lekach Tov): To stress that, had they had children, they would have inherited their father's position (and not Elazar and Isamar). 1
Yevamos, 64a: To teach us that whoever does not make the necessary effort to get married and have children is Chayav Misah. 2
Sifra (in Shemini): Because whoever takes precedence with regard to inheritance, takes precedence with regard to matters concerning prestige. See Torah Temimah, note 4, who elaborates.
What are the connotations of "Vayechahen Elazar ve'Isamar Al-P'nei Aharon Avihem"?
Rashi and Ramban #1: It means that Elazar and Isamar served as Kohanim in Aharon's lifetime. 1
Ramban #2: It is written with reference to the beginning of the Pasuk - Nadav and Avihu died ... in the lifetime (or in front of) Aharon their father.
Seforno: The Torah is informing us here that all of the above occurred in the lifetime of Aharon, including the anointing of the sons of Aharon with the anointing oil and the appointment of Elazar and Isamar to take charge of the Mishkan, which was ordered by Hashem and not by Aharon. 2
Midrash Rabah #1: It means that they served as Kohanim Gedolim in the lifetime of Aharon - Elazar when Aharon became Tamei, and Isamar, when Elazar too, became Tamei. 3
Midrash Rabah #2: It means that they served as Kohanim Gedolim after Aharon ha'Kohen died - Elazar after his death, Isamar, after the death of Elazar. 4
Oznayim la'Torah: It refers to their service in their capacity as princes of K'has (Elazar) and Gershon and Merari (Isamar).
Ramban: This in itself, is not a Chidush, since all Kohanim serve in the lifetime of their fathers (Refer to 3:4:3:3). The Torah is referring to the anointing as Kohanim Gedolim in their father's lifetime, to which future Kohanim Hedyotim were not subject. Refer also to 3:4:3.1:1,2 & 4.
Seforno: In future generations, Kohanim Hedyotim would not require anointing, and similar appointments would be made by the Kohen Gadol.
Oznayim la'Torah: This opinion did not want to assocoate Aharon with Tum'ah.
Oznayim la'Torah: Isamar died many years before Elazar, and that consequently, the Midrash must be referring to the descendents of Isamar, who took over the Kehunah Gedolah from those of Elazar for a short period - See also Torah Temimah, who elaborates.
What are the connotations of the words "Vayamas Nadav va'Avihu Lifnei Hashem"?
