Then Aaron lifted up his hands toward the people and blessed them, and he came down from offering the sin offering and the burnt offering and the peace offerings. And Moses and Aaron went into the tent of meeting, and when they came out they blessed the people, and the glory of the LORD appeared to all the people. And fire came out from before the LORD and consumed the burnt offering and the pieces of fat on the altar, and when all the people saw it, they shouted and fell on their faces.
Now Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it and laid incense on it and offered unauthorized fire before the LORD, which he had not commanded them. And fire came out from before the LORD and consumed them, and they died before the LORD. Then Moses said to Aaron, “This is what the LORD has said: ‘Among those who are near me I will be sanctified, and before all the people I will be glorified.’” And Aaron held his peace.
And Moses called Mishael and Elzaphan, the sons of Uzziel the uncle of Aaron, and said to them, “Come near; carry your brothers away from the front of the sanctuary and out of the camp.” So they came near and carried them in their coats out of the camp, as Moses had said. And Moses said to Aaron and to Eleazar and Ithamar his sons, “Do not let the hair of your heads hang loose, and do not tear your clothes, lest you die, and wrath come upon all the congregation; but let your brothers, the whole house of Israel, bewail the burning that the LORD has kindled. And do not go outside the entrance of the tent of meeting, lest you die, for the anointing oil of the LORD is upon you.” And they did according to the word of Moses.
(Leviticus 9:22-10:7 ESV)