1 Nisan · Yahrzeit
Nadav and Avihu - sons of Aharon HaKohen
Nadav and Avihu - sons of Aharon HaKohen
Yahrzeit - 1 Nisan
Burial place - the Sinai Desert
In Sha'ar HaGilgulim (Hakdama 31), the Arizal (peace be upon him) states that the souls of Nadav and Avihu came from a very high level of Adam - the level of nefesh of the world of Atzilut.
After their death, they returned again as an ibur (a new [higher] soul that enters a person while he is still alive) in Pinchas, son of Elazar, son of Aharon HaKohen.
In order to rectify their souls, Nadav and Avihu returned again, as an ibur or gilgul, in Eliyahu HaNavi, Shmuel HaNavi, Elisha HaNavi, King Chizkiyahu, Matityahu ben Yochanan Kohen Gadol the Hasmonean, Akavya ben Mahalalel, Rabbi Yochanan ben Zakkai, Rabbi Akiva, Rabbi Yeiva Saba (mentioned in the Zohar, Mishpatim), Abaye, and others... (Sha'ar HaGilgulim, Hakdama 36).
Nadav and Avihu were handsome young men (Targum Yonatan, Shemot 24:11).
They had no wives [because] they were haughty. Many women remained unmarried waiting for them, [but] they said: "Our father's brother [Moshe] is king, our mother's brother [Nachshon] is the head [of his tribe], our father [Aharon] is the Kohen Gadol [High Priest], and we are the deputies of the Kohen Gadol. What women are fit for us?" (Vayikra Rabbah 20:10).
What was the reason for the death of Aharon's sons
Rabbeinu Bechaye offers a kabbalistic explanation. He states that Nadav and Avihu saw the fire descend from heaven onto the altar. They recognized that this fire came from the heavenly place of Judgment. They were concerned that judgment would pass through the entire camp with destructive consequences. Therefore, they ran to offer incense, which was specifically intended to appease the forces of judgment. Nevertheless, they made one great mistake.
Whenever one wishes to avert the higher powers of judgment, it is not enough to try to appease them directly. For who has the power to appease the anger of G-d?
On the contrary, one must plead for and rely upon Divine mercy.
What needed to be done was to invoke the holy essential Name Havaya (the Tetragrammaton) and not attempt to go through other channels. This, then, was their sin. Their intentions were correct, but they carried them out improperly. It is clear to see how G-d judges in such a moment.
Nadav and Avihu were not commanded to do anything. But they took the initiative upon themselves. Nadav and Avihu did what they thought was right, without first consulting the established authorities of their father Aharon and their uncle Moshe.
It is interesting to note the manner of their death. Rabbeinu Bechaye states that two thin threads of fire came out of the Sanctuary (most likely from the Ark of the Covenant) and entered their nostrils, thereby removing (i.e. burning) their souls. This implies that physically nothing happened to them. Although it says that "fire came out from before G-d and consumed them," there was no evidence that they were burned.
Rabbi Yitzchak of Komarno in his book "Heichal Bracha" notes that the souls of Nadav and Avihu left their bodies in a state of union with Hashem, and that they ascended upward to cling to the Tree of Life. Therefore, although the actions of Nadav and Avihu were wrong, their intentions were pure. They were punished for their wrongful actions here in this world, and rewarded for their pure intentions in the World to Come.
Nadav and Avihu committed no other transgression besides this one. Wherever their death is mentioned, their sin is mentioned as well, so that people would not say: "They had hidden transgressions for which they died" (Vayikra Rabbah 20:8).
The death of Nadav and Avihu was recorded in several places [in the Torah] to show that G-d grieved over them, because Aharon's sons were beloved [by G-d] (Bamidbar Rabbah 2:23).
May the merit of Nadav and Avihu protect Am Yisrael!
(https://dailyzohar.com/tzadikim/185-Nadav-and-Avihu)