“Nadav and Avihu died before the Lord when they offered alien fire before the Lord in the wilderness of Sinai, and they had no children. Elazar and Itamar served as priests in the presence of Aaron, their father” (Numbers 3:4). “Nadav and Avihu died before the Lord.” In several places, the death of Nadav and Avihu is written: It teaches that there was sadness before the Omnipresent in their regard, as Aaron’s sons were beloved.
Likewise it says: “I will be sanctified through those who are near to Me” (Leviticus 10:3). “When they offered alien fire,” Rabbi Akiva says: They died due to the offering, as it is stated: “When they offered alien fire.” Rabbi Yosei says: They died due to drawing near,46They entered the Holy of Holies. as it is stated: “When they drew near before the Lord” (Leviticus 16:1). Rabbi Elazar says: It was also due to drawing near.
“An alien fire,” neither from the daily afternoon offering nor from the daily morning offering, but rather, lay fire,47As opposed to a holy fire. as it is stated: “An alien fire.” Bar Kappara says in the name of Rabbi Yirmeya bar Rabbi Elazar: Due to four factors Aaron’s sons died: Due to drawing near, due to the offering, due to alien fire…VaYikra Rabba, in Parashat Aḥarei Mot until “Many young donkeys have died and their hides have been spread over their mothers>.”48VaYikra Rabba 20:8–10.