Leviticus 10:1-3

And Nadab and Abihu, the sons of Aaron, took each of them his censer, and put fire therein, and laid incense thereon, and offered strange fire before Jehovah, which he had not commanded them. And there came forth fire from before Jehovah, and devoured them, and they died before Jehovah. Then Moses said unto Aaron, This is it that Jehovah spake, saying, I will be sanctified in them that come nigh me, and before all the people I will be glorified. And Aaron held his peace.