Leviticus 10:3

Then Moses said unto Aaron, This is it that the Lord spake, saying, I will be sanctified in them that come nigh Me, and before all the people I will be glorified. That was the explanation of this severe judgment. Since the two young men had omitted the proper preparation and had acted contrary to the commandment of the Lord, therefore He had sanctified Himself upon them by this punishment, which was to redound to His glory as the Holy One, who will not be mocked by disobedience. And Aaron held his peace; he was unable to gainsay the righteousness of the act of God, as set forth by Moses