Bar Kappara said in the name of Rabbi Yirmeya ben Elazar: Due to four matters Aaron’s sons died: For drawing near; for sacrificing; for alien fire; and because they did not take counsel from one another. For drawing near, because they entered the innermost sanctum; for sacrificing, because they sacrificed an offering regarding which they were not commanded; for alien fire, they brought in fire from a stove; and because they did not take counsel from one another, as it is stated: “Each took his fire pan” (Leviticus 10:1), each on his own, as they did not take counsel from one another.
Rabbi Yirmeya ben Elazar said: In four places,30Leviticus 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? It is to inform you [of their sin], so that all who enter the world will not have pretext to say: ‘They had clandestinely committed corrupt actions and that was the reason they died.’