Numbers 3:38-39

38And those that pitch before the tabernacle eastward, before the tent of meeting toward the sunrising, shall be Moses, and Aaron and his sons, keeping the charge of the sanctuary for the charge of the children of Israel; and the stranger that cometh nigh shall be put to death.

39All that were numbered of the Levites, which Moses and Aaron numbered at the commandment of the LORD, by their families, all the males from a month old and upward, were twenty and two thousand.