Numbers 4:27 At the commandment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burden, and in all their service; and you shall appoint their duty to them in all their responsibilities. (WEB)
Numbers 8:26 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." (See NIV)
1 Chronicles 23:32 and that they should keep the duty of the Tent of Meeting, and the duty of the holy place, and the duty of the sons of Aaron their brothers, for the service of the house of Yahweh. (See NIV)
2 Chronicles 31:16 besides those who were reckoned by genealogy of males, from three years old and upward, even everyone who entered into the house of Yahweh, as the duty of every day required, for their service in their offices according to their divisions; (See NIV)
2 Chronicles 31:17 and those who were reckoned by genealogy of the priests by their fathers' houses, and the Levites from twenty years old and upward, in their offices by their divisions; (See NIV)