Shemini. Nadav and Avihu's Sin

This week’s parsha depicts the excitement of the Mishkan inauguration and the shock of the deaths of the new priests, Nadav and Avihu, as:

“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 commanded them. And fire came forth from before the Lord and consumed them” (Vayikra/Leviticus 10:1-2)

What did Nadav and Avihu do wrong? Some say they were drunk (Rashi) on the basis of the warning, a few verses ahead:

“Do not drink wine or intoxicating drink, neither you nor your sons, when you enter the sanctuary and you will not die.” (10:9)

Other opinions are offered by the Midrash (see Vayikra Rabba 20:6-11) drawing on the language of the verse:

• “Before the Lord” - That they entered the Holy of Holies,