Nadav and Avihu, Aharon’s sons, each took his fire pan, put fire in them…and brought a foreign fire before Hashem that He had not commanded.[1]
We do not want for explanations regarding the sin of Nadav and Avihu. Among them are two that are found in Tanchuma.[2] The first sees them as transgressors for not marrying, and therefore not having children. The second describes them as wondering to each other when Moshe and Aharon would die, and they would then become the leaders of the people.
With all the many explanations we have for the sin of Nadav and Avihu, one premise is accepted by all: they were great tzadikim, and their death, tragic that it was, created a great kiddush Hashem. How, then, can we imagine them disregarding the halacha of producing children, and imagining them selfishly looking to the deaths of their father and uncle, so that they could claim the seat of power? Besides that, what do either of the explanations cited have to do with what our pasuk plainly states: They brought a strange, alien fire to the mizbeach?
It seems to me that Nadav and Avihu avoided marriage for a particular reason. They observed that Moshe’s sons were not the role models you might have hoped for from the children of this giant among men. They were concerned that many people would nonetheless look up to them, and therefore come up short. When they asked themselves why Moshe did not succeed in instilling greatness in his own children, they thought they had hit upon the answer. Moshe, they reasoned, was so busy tending to the tzibbur, that he could not devote sufficient time to his own family.
On the other hand, Nadav and Avihu noted that Aharon, their father, raised a family of extraordinary tzadikim. He was not as busy with community affairs as his brother, and spent more time with his children. At the same time, Aharon was great – but he did not approach the greatness of Moshe! Aharon, who invested much of his energy in his family, lacked the merit of complete devotion to the people.
They realized that they would assume the mantle of leadership after the passing of Moshe and Aharon. (This is what Chazal meant when they taught that Nadav and Avihu looked towards the death of Moshe and Aharon. They did not wish, for it, chalilah. But they looked at the new reality that their deaths would imply, and the leadership roles that would be thrust upon them.) They were uncomfortable with the choice they would have to make. They could throw themselves into community work, which risked selling their children short. They feared that any children they fathered would grow up to become models of mediocrity, and have a negative influence on the nation. Or, they could try to be perfect parents, but tend insufficiently to the community, which would mean that they would fail to achieve the greatest level of ruchniyus available to them. Best, they reasoned, would be to forgo having children, and devote themselves fully to Hashem!
They were full of passion and intense drive to be close to Hashem. But this passion was a “foreign fire.” The decision to devote themselves entirely to their spiritual mission was something “that He had not commanded.” Centuries later, Chizkiyahu prophetically foresaw that a future son would become a great evildoer (which in fact happened!), and decided not to have children to forestall his birth. For this, he was chastised by the navi: What business of yours are Hashem’s hidden matters? You are commanded by the Torah in pru u’revu!
Without the foreign fire of wanting too badly to stand always “before Hashem,” Nadav and Avihu would have realized the same.