Numbers 10:21

The other, i.e. the Gershonites and Merarites, as is evident both from their work and office, which was to take down and set up the tabernacle, Numbers 3:25,26 Numbers 4:22; and from Numbers 10:17, who therefore marched after the first camp, a good distance kern and before the Kohathites, that they might prepare the tabernacle for the reception of its utensils, which the Kohathites brought some time after them.