Ezra 2:62
These sought their register among those that were reckoned by genealogy, but they were not found: therefore were they deemed polluted and put from the priesthood.
Numbers 3:10
And thou shalt appoint Aaron and his sons, and they shall keep their priesthood: and the stranger that cometh nigh shall be put to death.
Leviticus 21:21-23
no man of the seed of Aaron the priest, that hath a blemish, shall come nigh to offer the offerings of Jehovah made by fire: he hath a blemish; he shall not come nigh to offer the bread of his God.
Numbers 16:39-40
And Eleazar the priest took the brazen censers, which they that were burnt had offered; and they beat them out for a covering of the altar,
Numbers 18:7
And thou and thy sons with thee shall keep your priesthood for everything of the altar, and for that within the veil; and ye shall serve: I give you the priesthood as a service of gift: and the stranger that cometh nigh shall be put to death.
Ezekiel 44:10-14
But the Levites that went far from me, when Israel went astray, that went astray from me after their idols, they shall bear their iniquity.