Leviticus 10:2

ותצא אש AND THERE WENT OUT FIRE — Rabbi Eleizer said: the sons of Aaron died only because they gave decisions on religious matters in the presence of their teacher, Moses (Sifra, Shemini, Mechilta d'Miluim 2 32; Eruvin 63a). Rabbi Ishmael said: they died because they entered the Sanctuary intoxicated by wine. You may know that this is so, because after their death he admonished those who survived that they should not enter when intoxicated by wine (vv. 8—9). A parable! It may be compared to a king who had a bosom friend, etc., as is to be found in Leviticus Rabbah 12:1, 4 (cf. Biur).

וַתֵּ֥צֵא אֵ֛שׁ מִלִּפְנֵ֥י יְהֹוָ֖ה וַתֹּ֣אכַל אוֹתָ֑ם וַיָּמֻ֖תוּ לִפְנֵ֥י יְהֹוָֽה׃

And a fire went out from the Lord, and devoured them, and they died before the Lord.