Leviticus 10:1-3

Aaron’s sons Nadab and Abihu each took his own firepan, put fire in it, placed incense on it, and presented unauthorized fire before the LORD, which he had not commanded them to do. Then fire came from the LORD and consumed them, and they died before the LORD. Moses said to Aaron, “This is what the LORD has spoken: I will demonstrate my holiness to those who are near me, and I will reveal my glory before all the people.” And Aaron remained silent.