“Everything is in the hands of heaven except the fear of heaven.”
– Talmud, Tractate Berakhot 33b
The Sages teach that both love and fear are necessary in our avodah our service to H’Shem. What is our avodah? Prayer from the heart. Chasidism teaches that prayer only ascends to the L-RD on two wings – love and fear. Nadav and Avihu may have over-exemplified the “love component” in their service (avodah) to H’Shem. They sought to draw near to the L-RD; yet, they did so in a way that was disrespectful to Him. Although they had good intentions, they did not exhibit the necessary component of fear of the L-RD, inasmuch as they disregarded the fact that they had not been commanded to perform this particular incense service. They did not have permission from the L-RD to approach the Mishkan (Sanctuary).
Immediately following their deaths, Aaron receives an admonition: “Drink no wine nor strong drink, thou, nor thy sons with thee, when ye go into the tent of meeting that ye die not; it shall be a statute forever throughout your generations. And that ye may put difference between the holy and the common, and between the clean and the unclean” (Leviticus 10:9-10, JPS 1917 Tanach). This implies that one of the reasons Nadav and Avihu were consumed by the fire of the L-RD was because they were intoxicated, when they brought their incense offering.
“And the L-RD spoke unto Moses, after the death of the two sons of Aaron, when they drew near before the L-RD, and died; and the L-RD said unto Moses: ‘Speak unto Aaron thy brother, that he come not at all times into the holy place within the veil, before the ark-cover which is upon the ark; that he die not; for I appear in the cloud upon the ark-cover’” (Leviticus 16:1-2, JPS 1917 Tanach). Here the Torah infers another reason for the deaths of Nadav and Avihu.
Whereas the Torah previously records that that they approached the Mishkan (Sanctuary). Here the Torah infers that they approached the L-RD’s presence that would appear between the two golden cherubim on the kapores (Ark cover). When Aaron is admonished in this passage, not to enter the Kadosh Kadoshim at all times (only once-a-year on Yom Kippur) this implies that Nadav and Avihu entered the Kadosh Kadoshim behind the paroches, the curtain that separated the inner sanctuary where the ark of the covenant was kept, from the rest of the Mishkan.
“Sanctify yourselves therefore, and be ye holy; for I am the L-RD your G-d.”
– Leviticus 20:7, JPS 1917 Tanach