Numbers 18:5

³And they shall keep thy charges, and the charges of the tabernacle; only they shall not approach the holy vessels and the altar, so both they and you shall not die.

⁴And they shall be joined to thee, and shall keep the charges of the tabernacle of witness, in all the services of the tabernacle; and a stranger shall not approach to thee.

— Numbers 18:5 —

⁶And I have taken your brethren the Levites out of the midst of the children of Israel, a present given to the Lord, to minister in the services of the tabernacle of witness.

⁷And thou and thy sons after thee shall keep up your priestly ministration, according to the whole manner of the altar, and that which is within the veil; and ye shall minister in the services as the office of your priesthood; and the stranger that comes near shall die.