'Duties' in the Bible

but shall minister with their brothers in the Tent of Meeting, to perform the duty, and shall do no service. You shall do thus to the Levites concerning their duties."

Thus I cleansed them from all foreigners, and appointed duties for the priests and for the Levites, everyone in his work;

and who does not any of those [duties], but even has eaten on the mountains, and defiled his neighbor's wife,