Leviticus 10:1

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.

Surrounding context

10:1 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.

10:2 So fire went out from the LORD and devoured them, and they died before the LORD.

Translation and sources