from a son of thirty years and upward, you shall number them, until a son of fifty years, all that enter to wait on the service, to serve in the tabernacle of the congregation.
This is that which pertains to the Levites: from twenty-five years old and upward he shall go in to serve for service, and the works of the tabernacle of the congregation.
But he shall serve with his brothers in the tabernacle of the congregation, to keep the charge; only he shall not serve at a service. So you shall do to the Levites concerning their charge.