Numbers 1:51

51. The stranger that cometh nigh Every non-Levite is prohibited from intrusion upon the sacred precincts. So, also, with respect to the priestly office, every Levite not an Aaronic priest is a stranger. The profaned censers used by Korah the Levite, and his host of princes, were made into plates for the covering of the altar, “to be a memorial (warning) unto the children of Israel, that no stranger, which is not of the seed of Aaron, come near to offer incense before the Lord.” Numbers 16:36-40.

Shall be put to death We find no directions to the Hebrew judiciary in such a case, and no instance of the infliction of the death penalty for this sacrilege by the human magistrate, but a record of the special interposition of Jehovah in the case of Nadab and Abihu, (Leviticus 10:1-2,) supposed to have been drunk, because of the prohibition of wine immediately subjoined, (Leviticus 10:8-10,) and also of Uzzah, 1 Chronicles 13:10. Hence we infer that this crime was punished by the immediate stroke of the Divine hand only. To the objection that this punishment was too severe and too summary, we reply that it was designed to teach the holiness of God in an impressive manner. We know too little of the Divine government to criticise its acts.