Moses, Aaron, and his sons, who performed the duties of the sanctuary as a service on behalf of the Israelites, camped in front of the tabernacle on the east, in front of the tent of meeting toward the sunrise. Any unauthorized person who came near it was to be put to death.

But they shall minister with their 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 as to their duties.

Therefore thou and thy sons with thee shall keep your priest's office for every thing of the altar, and within the vail; and ye shall serve: I have given your priest's office unto you as a service of gift: and the stranger that cometh nigh shall be put to death.