Jeremiah 33:20-21

20“I, Lord, make the following promise: ‘I have made a covenant with the day and with the night that they will always come at their proper times. Only if you people could break that covenant

21could my covenant with my servant David and my covenant with the Levites ever be broken. So David will by all means always have a descendant to occupy his throne as king and the Levites will by all means always have priests who will minister before me.