Lectures on the weekly Torah reading by the faculty of
The Sin of Aaron’s Sons
Now Aaron’s sons Nadab and Abihu each took his fire pan, put fire in it, and laid incense on it; and they offered before the Lord alien fire, which He had not enjoined upon them. And fire came forth from the Lord and consumed them; thus they died before the Lord. (Lev. 10:1-2)
Ostensibly Scriptures describe precisely the sin committed by Nadab and Abihu and the severe punishment that they received, but in truth the detailed facts are anything but clear to us, and many different views have been presented in the works of the Sages and biblical commentators. Here we shall take a close look at the text to find details that might help us understand the actions and motives of Aaron’s sons.
1. The family relationship of the sinners – “Aaron’s sons” – is given before their names.
2. Scriptures specify both that they put fire in their pans and laid incense on it.
3. When it says that they offered “before the Lord,” does this description of where the action took place refer to the entire Tabernacle, or to a specific part of it?
4. What is “alien fire”? Does this mean the incense or the fire itself? And in what way was it alien?
5. What purpose is served by addition of the words, “which He had not enjoined upon them”?
6. What is signified by Moses saying in the name of the Lord, “Through those near to Me I show Myself holy” (Lev. 10:3)?
Regarding the fire, we find no prohibition in the Torah against “alien fire.” Although the priest who offers the incense is supposed to take the fire from the altar of burnt offerings,  there is no reason to assume that Aaron’s sons did otherwise, not taking the fire for their incense from the altar for burnt offerings, since even before the fire came down from heaven Aaron had offered portions of sacrifice on the altar (Lev. 9:10,13), and also during the preceding seven days of consecration sacrifices had been offered and burned on the altar (Lev. 8:14-28). Also, since “a perpetual fire shall be kept burning on the altar, not to go out” (Lev. 6:6), one may presume that there was sacred fire burning on the sacrificial altar at that time.
We must bear in mind that the fire that descended from heaven on the eighth day was not for dedication of the altar (as in the account of the dedication of the altar by heavenly fire, found in II Chronicles 7:1-3);  the altar had already been dedicated by Moses, when he offered up a burnt offering and a meal offering on the day the Tabernacle was erected (Ex. 40:29). Thus the fire that descended from heaven on the eighth day was to consume the offerings that had already begun to be burned by the earthly fire that was used when they had been offered on the altar, as if the Lord were giving His blessing to the deeds of human beings. Therefore, since one cannot assume by the plain sense of the text that Aaron’s sons brought fire to their incense from the “cooking house,”  i.e., non-sacred fire brought from people’s tents, we can only say that their sin had not been in using alien and forbidden fire, and we must assume that the sin and alien nature lay in the incense. This understanding is supported by the language used here and by parallel situations:  “They offered before the Lord alien fire” – the fire itself was not an offering, rather a means for giving an offering.
So why did Scripture use the expression “alien fire”? Two reasons can be given: one is linguistic and stylistic, the other substantive and halakhic. Linguistically, since the previous verse (Lev. 9:24) mentions fire coming from the Lord to burn the portions of sacrifice on the altar, and the following verse has fire coming from the Lord to burn up the sons of Aaron, the intermediate verse between them speaks of fire, so the linguistic association stems from an internal connection: the divine fire that descended to the altar brought on the act of fire by the sons of Aaron, and by divine fire they were punished. In other words, we have human fire between two instances of divine fire: the former, fire of blessing; the latter, fire of curse; and the human fire between them being what caused the reversal.
As for the substantive-halakhic explanation: in the laws concerning the incense altar (Ex. 30:1-10) it says: “You shall not offer alien incense on it” (Ex. 30:9); whether the prohibition there is against incense given of freewill, not explicitly commanded, or whether the prohibition is against incense which has not been properly prepared according to the commandment, it always concerns incense which is offered especially on the incense altar. In contrast, in the story of Aaron’s sons, the incense was in fire pans; perhaps the expression, “alien incense,” used by the above-mentioned law does not apply to what Aaron’s sons were doing, and therefore here the expression “alien fire” was used.
So wherein lay their sin? As the Sages said,  in drawing close and in sacrificing. The two can be joined together: they offered an unacceptable sacrifice and in so doing drew close to a place they were not permitted to approach. Wherever Nadab and Abihu may have performed their act, it comes out the same. If their incense was made as prescribed by the Torah, it was forbidden to burn it outside the Tabernacle (loc. sit., 38), and if it was not as the Torah prescribed, surely it was forbidden to bring it into the Tabernacle. However, even incense that has been properly prepared, is forbidden to be offered in the Tabernacle if it has not been explicitly commanded: we find no mention in the laws of the Torah of any freewill offering of incense, as there are freewill burnt offerings, sacrifices of well-being and freewill meal offerings. Perhaps the underlying reason for this difference lies in the special expiatory function reserved for incense, and therefore in the sin of Aaron’s sons the emphasis is put on their having done something “which He had not enjoined upon them” (Lev. 10:1).
Yom Kippur and Nadav and Abihu
Where did Nadab and Abihu approach with their fire pans? We cannot assume that they brought their fire pans into the sacred precinct within the Tabernacle (paralleling the Heikhal or Sanctuary in the Temple), for that was where the incense altar stood and presumably Aaron had already burned incense there as part of the regular morning sacrifice (Lev. 9:16), so what would fire pans with incense have added there? Hence it appears that they must have entered the Holy of Holies with their fire pans, “and they offered before the Lord” (Lev. 10:1), as well as “died before the Lord” (Lev. 10:2). Therefore the laws prescribing the ritual of expiation on the Day of Atonement (Lev. Ch.16), which were given to Moses “after the death of the two sons of Aaron who died when they drew too close to the presence of the Lord,” begin with words of warning: “Tell your brother Aaron that he is not to come at will into the Shrine behind the curtain [i.e., into the Holy of Holies], ... lest he die” (Lev. 16:2). Further on it says that only on a special day, and for a special purpose, in a special manner and dressed in special garments, may the High Priest enter the Holy of Holies with incense on his fire pan. From this, especially from the association of this passage with the death of Aaron’s sons, we learn that their sin lay in the same matter: in entering and bringing in with them to the Holy of Holy fire pans of incense, which they neither had been specifically commanded to do nor had specially prepared.
Now we can ask what led these two brothers to perform this ritual act, which was lofty yet unacceptable? The Sages’ response has two aspects to it. The positive aspect is explained in Torat Kohanim (Shemini 1.32): “Aaron’s sons ... each took – they too, in their rejoicing, having seen new fire, wished to add further devotion upon devotion.” The negative aspect views the act of Nadab and Abihu, and their punishment, as a continuation of what we were told in Exodus 24:1. Aaron’s two older sons had become proud of heart because of ascending Mount Sinai, close to the Divine Presence, with Moses and Aaron and without Aaron’s younger two sons, Eleazar and Ithamar, as explained in Torat Kohanim (Shemini 1.21): “Having seen Moses and Aaron in the lead, and themselves following behind, and the rest of the Israelites after them, Nadab said to Abihu: As soon as these two old men die, we shall be the leaders of the community.” In other words, these two brothers, Aaron’s sons, saw themselves as shortly inheriting the status of the two older men, the brothers Aaron and Moses; apparently it was clear already that Moses’ sons were not worthy of inheriting his status and position.
Korah and Aaron’s Sons
If we tend to favor the view which sees the act of Aaron’s sons as primarily motivated by the negative desire to seize power, this comes from a comparison with a similar event in the Torah, namely the uprising by Korah and his following. Indeed, drawing such a comparison is essential, since without it the story of Korah raises grave questions: Dathan and Abiram, who were swallowed up by the earth (Num. 16:32-33), had been warned beforehand regarding the punishment that awaited them (Num. 16:30), whereas Korah and his followers had been told beforehand that only one of the persons with the incense pans would be chosen to serve the Lord (Num. 16:5-7), but they had not been told how those that would be rejected would be punished. How can one punish without first giving warning? We can only say that Nadab and Abihu being burned was a precedent for Korah and his followers and was to serve them as a warning:  he who offers incense without having been chosen to do so, is doomed to die by being consumed by fire.
Just as the story of Korah needs the story of Aaron’s sons and deduces a message from it, so too the story of Korah is instructive in understanding the story of Aaron’s sons, since both these episodes involve a struggle for power. Perhaps – and this is mere surmise – Aaron’s two younger sons, Eleazar and Ithamar, had finer qualities than their older brothers, Nadab and Abihu, and the latter’s act was intended as a sort of “coup” designed to seize the priesthood  on the day that a routine pattern was first instituted for the priestly service in the Tent of Meeting.
Midrash Kohanim (Aharei Mot 1.1) lists other transgressions in Nadab and Abihu’s act: that they neither consulted each other prior to acting, nor did they ask the advice or instruction of Moses – behavior which attests to their pride. The same goes for what Leviticus Rabbah adds (20.10) – “they were haughty,” for they had not married since they deemed no woman worthy of them, so high was their status. That they were bachelors is proven by Scripture’s remark, “they left no sons” (Num. 3:4), since it is unlikely that they would both have been childless. The midrash (loc. sit., 9) emphasizes that their being unmarried actually made them ineligible for the high priesthood. 
In the final analysis, the view of Nadab and Abihu as presumptuously wishing to seize power does not contradict the interpretation that they put fire in their incense pans out of religious fervor and devotion; a person who has a high level of religiosity could believe that by doing this he would achieve a position of leadership, and even might aspire to such. For who can delve into the depths of a person’s soul?
In view of all this, the explanation that Moses gave Aaron, “Through those near to Me I show Myself holy, and gain glory before all the people” (Lev. 10:3), should be understood in terms of the repeated use of the root k-r-v (=“be close,” also “sacrifice”) in the Torah’s narrative about Nadab and Abihu.  “Through those near to Me,” those who draw near to the Lord to serve Him in the innermost sanctum of the Temple, through them the Lord wishes to be sanctified. How? by having this ritual performed according to the exact specification of the commandments. In this way the Lord will “gain glory before all the people,” the Lord will be greatly respected by Israel.
 See Mishnah Tamid 5.5. There are no grounds for assuming that it was ever otherwise.
 Maccabees II, 1:31-32, recounts similarly regarding dedication of the Second Temple.
 According to Leviticus Rabbah 20.8.
 16:1; Numbers 20:4, 26:61.
 Torat Kohanim Aharei Mot 1.2; Leviticus Rabbah 20.8.
 In a similar vein, cf. Tanhuma Buber ed., Korah 11; Tanhuma Korah 5; Numbers Rabbah 18.8.
 Preferring the younger son over the less worthy first-born is a well-known motif in Scripture. With respect to attempted coups, see II Sam. 3:7, ibid., 16:20-22. Perhaps also I Kings 2:14-22; Gen. 35:22.
 Mishnah Yoma 1.1
 See note 4.