Dvar Torah by Rabbi Abraham J. Twerski
The Torah states: “The sons of Aaron, Nadab and Abihu, each took his fire-pan, put fire in them and placed incense upon it; and they brought before God an alien fire that He had not commanded them” (Lev. 10:1).
Rashi cites the statement of Reb Yishmael in the Talmud that the transgression of Nadab and Abihu was that they drank wine before entering the Sanctuary. This statement appears remarkable. The Torah explicitly says that their sin was they brought an “alien fire”. How and why does Reb Yishmael give another reason, which seems to contradict the Scripture?
Nadab and Abihu were extraordinarily great men, so much so that Moshe said that he considered them greater than himself and Aaron (Rashi, Lev. 1:3). If they drank wine before entering the Sanctuary, it was not because they were out partying. Rather, they knew that in the Sanctuary they would have a spiritual experience. They believed that by drinking wine they would attain a state of mind more conducive to a spiritual experience. After all, the Psalmist says, “Wine makes glad the heart of man” (Psalm 104:15). By relieving a person’s tension, wine enables one to have greater joy, and joy can enhance a spiritual experience. It was for the intensification of the spiritual experience that they drank wine.
Why, then, were they so severely punished? Because one should not seek to enhance a spiritual experience by artificial means. Intense spiritual experiences should come as a result or prayer, Torah study, meditation with contemplation on the Infinite — and doing the mitzvos — not by altering the metabolism of the brain with a chemical. Nadab and Abihu’s attempt to enhance the experience by drinking wine was introducing “an alien fire” into the Divine service.