Numbers 4:1

1 And the Lord said to Moses and Aaron,

2 Let the sons of Kohath, from among the sons of Levi, be numbered by their families, in the order of their fathers' houses;

3 All those from thirty to fifty years old who are able to do the work of the Tent of meeting.

4 And this is to be the work of the sons of Kohath in connection with the most holy things.

5 When all the people go forward, Aaron is to go in with his sons, and take down the veil of the curtain, covering the ark of witness with it;

6 And putting over it the leather cover and over that a blue cloth; and putting its rods in place.

7 And on the table of the holy bread they are to put a blue cloth, and on it all the vessels, the spoons and the basins and the cups; and the holy bread with them;