Leviticus 10:1-3

Then Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it, put incense on it, and offered profane fire before the LORD, which He had not commanded them. So fire went out from the LORD and devoured them, and they died before the LORD. And Moses said to Aaron, “This is what the LORD spoke, saying: ‘By those who come near Me I must be regarded as holy; And before all the people I must be glorified.’ ” So Aaron held his peace.