Ezra 2:62
These sought their register among those that were reckoned by genealogy, but they were not found; therefore, they were, as polluted, put from the priesthood.
Numbers 3:10
And thou shalt appoint Aaron and his sons that they shall guard their priesthood; and the stranger that comes near shall be put to death.
Leviticus 21:21-23
No man that has a blemish of the seed of Aaron, the priest, shall come near to offer the offerings of the LORD made by fire. He has a blemish; he shall not come near to offer the bread of his God.
Numbers 16:39-40
And Eleazar, the priest, took the brass censers with which those that were burnt had offered, and they were made into a broad covering of the altar
Numbers 18:7
Therefore thou and thy sons with thee shall keep your priesthood for every thing of the altar and within the veil, and ye shall minister; for I have given the service of your priesthood as a gift, and the stranger that comes near shall die.
Ezekiel 44:10-14
And the Levites that are gone away far from me, when Israel went astray, which went astray away from me after their idols; they shall bear their iniquity.