Ezekiel 44:15-16

15Only the priests who are descendants of Zadok, the Levite, may come near to me and serve me. When Israel's people turned away from me, only the priests of Zadok's family faithfully served me in my temple. So now Zadok's descendants may offer to me the fat and the blood of sacrifices. That is what the Almighty Lord says.

16Only they can come into my holy place and serve me at the altar. They will do what I tell them to do.