Put the holy ark etc - The ark of the covenant may have been temporarily removed from the holy of holies while Josiah effected necessary repairs.
It shall not be a burden upon your shoulders - The removing and replacing the ark Josiah means “shall not henceforth be your duty. The ark shall remain undisturbed in the holy of holies. You shall return to your old employments, to the service of God and the instruction of the people.”