Divrey Hayamim Alef 23:28 OJB

28 Because their ma'amad (position) was to wait on the Bnei Aharon for the avodas Beis Hashem, in the khatzerot, and in the rooms, and in the tahorat (cleansing) of kol kodesh, and the work of the avodas Beis HaElohim;