Numbers 18:2-4

2Bring with you your brothers, the tribe of Levi, the tribe of your father, so that they may join you and assist you, both you and your sons with you, before the Tent of the Testimony.

3They are to perform their duties for you and for all matters related to the Tent. They must not approach the implements of the Sanctuary or the altar—otherwise, both you and they will die.

4They are to team with you and attend to the Tent of Meeting, for all the service of the Tent. But no unauthorized person may intrude upon you.