Num Numbers, chapter Book of Numbers, chapter 18

And take with thee thy brethren also of the tribe of Levi, and the sceptre of thy father, and let them be ready in hand, and minister to thee: but thou and thy sons shall minister in the tabernacle of the testimony. And the Levites shall watch to do thy commands, and about all the works of the tabernacle: only they shall not come nigh the vessels of the sanctuary nor the altar, lest both they die, and you also perish with them.