Numbers 4:4

²  Take the sum of the sons of Kohath from among the sons of Levi, after their families, by the house of their fathers,

³  From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.

⁴  This shall be the service of the sons of Kohath in the tabernacle of the congregation, about the most holy things:

⁵  And when the camp setteth forward, Aaron shall come, and his sons, and they shall take down the covering vail, and cover the ark of testimony with it:

⁶  And shall put thereon the covering of badgers' skins, and shall spread over it a cloth wholly of blue, and shall put in the staves thereof.