Numbers 2:17
The Tribe in the Center
2:17 “Then the tent of meeting with the camp of the Levites will travel in the middle of the camps. They will travel in the same order as they camped, each in his own place under his standard.
Numbers 4:19
4:19 but in order that they will live and not die when they approach the most holy things, do this for them: Aaron and his sons will go in and appoint each man to his service and his responsibility.