Numbers 16:5, 7, 10, 35, 40, 46-48

and he spoke to Korah and all his company, saying, “In the morning the LORD will show who belongs to Him, and who is holy, and will bring him near to Himself; the one whom He will choose He will bring near to Himself. [2 Tim 2:19]

then put fire in them and place incense on them in the presence of the LORD tomorrow; and the man whom the LORD chooses shall be the one who is holy. You have gone far enough, you sons of Levi.”

and that He has brought you near [to Him], Korah and all your brothers, sons of Levi with you? Would you seek the priesthood also?

Fire also came forth from the LORD and consumed the two hundred and fifty men who were offering the incense.

as a reminder to the sons of Israel so that no layman—that is, one who is not of the descendants of Aaron should approach to offer incense before the LORD; so that he will not become like Korah and as his company—just as the LORD had said to him through Moses.

Moses said to Aaron, “Take a censer and put fire in it from the altar and lay incense on it; then bring it quickly to the congregation and make atonement for them, for wrath has gone forth from the LORD; the plague has begun!” So Aaron took the burning censer as Moses commanded, and ran into the midst of the assembly; and behold, the plague had [already] begun among the people; and he put on the incense and made atonement for the people. He stood between the dead and the living, so that the plague was brought to an end.