וַיַּקְרִיבוּ לִפְנֵי יְהוָֹה אֵשׁ זָרָה אֲשֶׁר לֹא צִוָּה אֹתָם – and they brought before the Lord foreign fire, which He had not commanded them.
On the day of their installation, wearing their priestly vestments, Nadab and Abihu were overcome by ecstasy and by the desire to express their emotions. The incense that they burned was identical to that which their father Aaron had offered. But there was one significant difference. Aaron was obeying God’s will, while Nadab and Abihu performed an action that God had not commanded.
The sin of Nadab and Abihu illustrates a dichotomy in one’s approach to religious observance: religious divine service, with its accompanying discipline, versus ceremonial experience. A mitzvah is not merely a perfunctory action. It must also translate into experiential terms. The Torah demands that we experience joy and satisfaction when we perform a mitzvah.
There are two ways to achieve that exalted state: the Jewish way and the pagan way. The Jewish way requires us to fashion our lives according to God’s discipline, as illustrated by the word וְצִוָּנוּ.
The reason we perform the mitzvah is our absolute surrender to God’s will. Eventually, we must progress from that surrender to a profound spiritual experience that encompasses our entire being. Prayer begins as an obligatory, even compelled act, with rigid requirements of time, location, and behavior. We are particularly aware of this during the winter or in inclement weather when we must venture out into the cold for minyan early in the morning and at night. However, as we progress in our relationship to prayer, we feel the rewards of intimate communion with God.
The pagan approach, which is the antithesis of the Torah approach, begins with excitement and culminates in sin and disillusionment. It very much parallels the approach of the modern world, where one uses drugs or alcohol to create an artificial feeling of euphoria, masking one’s actual life situation of disappointment and futility.
Korah erred in this matter, confusing the ceremonial with God’s command. According to the Sages, Korah attempted to discredit Moses by posing two questions: If a person wears a garment that is made entirely of techeles (the biblically-mandated blue of the tzitzis fringe), is it valid for the fulfillment of the mitzvah of tzitzis? If a house is filled with sacred books, must a mezuzah still be affixed to its doorpost? When Moses said yes to both questions, Korah mocked him (Yalkut Shimoni Korach 750). Korah’s error was his undue focus on the ceremonial aspect of the mitzvah while ignoring the aspect of God’s command, which is the most important.
The transgression of Nadab and Abihu, whom the Torah describes as sanctified, was that they brought before the Lord foreign fire, which He had not commanded them. The divine command and our discipline in obeying that command are the only healthy routes to religious inspiration. Any deviation is unacceptable and ultimately doomed to failure. (Darosh Darash Yosef, pp. 223-226)