Leviticus 10:1-3

Living Bible

10 But Nadab and Abihu, the sons of Aaron, placed unholy fire in their censers, laid incense on the fire, and offered the incense before the Lord^[a]—contrary to what the Lord had just commanded them! ² So fire blazed forth from the presence of the Lord and destroyed them.

³ Then Moses said to Aaron, “This is what the Lord meant when he said, ‘I will show myself holy among those who approach me, and I will be glorified before all the people.’” And Aaron was speechless.