Midrash sa Mga Bilang 26:61: Midrash Tanchuma Buber, Bamidbar Rabbah, Sifra & Midrash Tanchuma

Another interpretation (of Eccl. 7:1): A GOOD NAME IS BETTER THAN GOOD OIL. The Names of Hananiah, Mishael, and Azariah were <better> than the good oil with which Nadab and Abihu were anointed.⁴Exod. 29:41. Why? The children of Aaron went in to sacrifice and were burned;⁵Lev. 10:1–2; Numb. 3:4; 26:61. Hananiah, Mishael, and Azariah were thrown into the midst of a fiery furnace and were saved.⁶Dan. 1:6–7; 3:8–26. Ergo (in Eccl. 7:1): A GOOD NAME.

Rabbi Yirmeya ben Elazar said: In four places,⁴⁹Leviticus 10:1, 16:1; Numbers 3:4, 26:61. it mentions the death of Aaron’s sons, and in all of them it mentions their sin. Why to that extent? It is to inform you that they had committed only this sin alone. Rabbi Elazar HaModa’i said: Come and see how difficult the death of Aaron’s sons was before the Holy One blessed be He, as every place that it mentions their death, it mentions their sin. Why to that extent? To prevent the possibility of slander, so that people should not say: ‘They clandestinely committed corrupt actions and that was the reason they died.’
“Nadav and Avihu died before the Lord.” Rabbi Yoḥanan said: Did they die before the Lord? It teaches that it is difficult before the Holy One blessed be He when the children of the righteous die during their fathers’ lifetimes.
“When they offered alien fire before the Lord,” Rabbi Yoḥanan of Yafo raised a question before Rabbi Pinḥas bar Ḥama in the name of Rabbi Simon: Here [in this verse] it says “before the Lord,” “before the Lord,” twice, but elsewhere⁵⁰The same midrash appears in Midrash Rabba Acharei Mot 20:10 and was apparently copied over to here without correcting the references. In the context of Bamidbar it should say "Elsewhere [in this verse] it says “before the Lord,” “before the Lord,” twice, but here is says…" it says: “In the presence of Aaron their father,” once. This teaches that it was twice as difficult before the Holy One blessed be He as it was for their father.

2) "when they drew near before the L–rd and they died": R. Yossi Haglili says: They died because of the drawing near (and entering the holy of holies without permission), and not because of the incense offering. R. Akiva says: They died because of the offering and not because of the drawing near. One verse (our verse) states "when they drew near before the L–rd and they died," and another verse states (Vayikra 11:1) "and they offered before the L–rd a strange fire." The resolution (Bamidbar 3:4) "when they drew near (with) a strange fire before the L–rd" — They died because of the drawing near and not because of the offering. R. Elazar b. Azaryah says: The offering is sufficient (for death) unto itself, and the drawing near is sufficient unto itself.