Numbers 3:38-39

38Moses, Aaron, and his sons, who performed the duties of the sanctuary as a service on behalf of the Israelites, camped in front of the tabernacle on the east, in front of the tent of meeting toward the sunrise. Any unauthorized person who came near it was to be put to death.

39The total number of all the Levite males one month old or more that Moses and Aaron registered by their clans at the Lord’s command was 22,000.