Numbers 4:14

and they shall lay thereon all the utensils with which they minister at it, namely the censers, and the flesh-forks, and the cups, and the cover, and the vials, and all the utensils of the altar; and they shall throw over it a skin covering of blue, and put in the staves to carry it. Then they shall take a purple mantle, and cover the laver and its base; and put it in a skin covering of blue, and put it on the staves.