'Priests and Levites' in the Bible

This is the thing that you must do: one third of you priests and Levites {coming off duty on the Sabbath} [shall be] gatekeepers at the entrances

And Hezekiah appointed working groups of the priests and the Levites, each according to their divisions, {according to the service for priests and Levites}, for burnt offerings, for peace offerings, to serve, to give thanks, and to praise in the gates of the camps of Yahweh.