'Duty' in the Bible

He said to me, This room, whose prospect is toward the south, is for the priests, the keepers of the duty of the house;

and the room whose prospect is toward the north is for the priests, the keepers of the duty of the altar: these are the sons of Zadok, who from among the sons of Levi come near to Yahweh to minister to him.

You have not performed the duty of my holy things; but you have set performers of my duty in my sanctuary for yourselves.

Yet will I make them performers of the duty of the house, for all its service, and for all that shall be done therein.

But the priests the Levites, the sons of Zadok, who performed the duty of my sanctuary when the children of Israel went astray from me, they shall come near to me to minister to me; and they shall stand before me to offer to me the fat and the blood, says the Lord Yahweh: