Ezekiel 44:10-11

But the Levites who went far away from Me when Israel went astray, who went astray from Me after their idols, they shall bear the punishment for their sin and guilt. Yet they shall minister in My sanctuary, having oversight [as guards] at the gates of the temple and ministering in the temple. They shall slaughter the burnt offering and the sacrifice for the people, and they shall stand before them to minister to them.