Vayikra 10:1-2

Orthodox Jewish Bible

10 And Nadav and Avihu, the bnei Aharon, each took his censer, and put eish therein, and put ketoret (incense) thereon, and offered eish zarah (strange, unauthorized fire) before Hashem, which He commanded them not.

² And there went out eish (fire) from the presence of Hashem, and devoured them, and they died before Hashem.