Numbers 3:38-39

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

39All that were numbered of the Levites, whom Moses and Aaron numbered at the commandment of Jehovah, according to their families, all the males from a month old and upward, were twenty-two thousand.