Jeremiah 33:18-22

18neither shall there fail to the priests the Levites a man before me to offer up burnt-offerings, and to burn oblations, and to do sacrifice continually.

19And the word of Jehovah came to Jeremiah, saying,

20Thus saith Jehovah: If ye can break my covenant [in respect] of the day, and my covenant [in respect] of the night, so that there should not be day and night in their season,

21[then] shall also my covenant be broken with David my servant, that he should not have a son to reign upon his throne; and with the Levites, the priests, my ministers.

22As the host of the heavens cannot be numbered, nor the sand of the sea measured, so will I multiply the seed of David my servant, and the Levites that minister unto me.