Numbers 3:38-39

38The area in front of the Tabernacle, in the east toward the sunrise, was reserved for the tents of Moses and of Aaron and his sons, who had the final responsibility for the sanctuary on behalf of the people of Israel. Anyone other than a priest or Levite who went too near the sanctuary was to be put to death.

39When Moses and Aaron counted the Levite clans at the Lord’s command, the total number was 22,000 males one month old or older.