Numbers 4:3-5

Douay-Rheims 1899 American Edition

³ From thirty years old and upward, to fifty years old, of all that go in to stand and to minister in the tabernacle of the covenant.

⁴ This is the service of the sons of Caath:

⁵ When the camp is to set forward, Aaron and his sons shall go into the tabernacle of the covenant, and the holy of holies, and shall take down the veil that hangeth before the door, and shall wrap up the ark of the testimony in it,