Ezekiel 40:44-46

44Outside the inner gate, within the inner court, were two rooms, one at the side of the north gate and facing south, and another at the side of the south gate and facing north. 45He said to me, “The room facing south is for the priests who guard the temple, 46and the room facing north is for the priests who guard the altar. These are the sons of Zadok, who are the only Levites who may draw near to the Lord to minister before him.”