Ezekiel 40:44-46

Then he brought me into the inner courtyard just outside the north gate. Behold, I saw chambers for the singers of the inner court, one on the side of the north gate, facing south, the other on the side of the south gate, facing north. The shining man told me, “The chamber facing south is for the priests responsible for the service of the temple. And the chamber facing north is for the priests responsible for the sacrifices of the altar. These are the sons of Zadok, for only the sons of Levi are permitted to go into YAHWEH’s presence to serve him.”