Numbers 2:32-36

These are the numbered men of the sons of Israel by their fathers’ households; the total of the numbered men of the camps by their armies, 603,550.

The Levites, however, were not counted among the sons of Israel, just as the Lord had commanded Moses.

So the sons of Israel did all this; according to all that the Lord commanded Moses, so they camped by their flags, and so they set out, everyone by his family according to his father’s household.