Sforno on Numbers 4:26/ספורנו על במדבר ד׳:כ״ו

1ועבדו, during the periods when the Israelites were encamped their duties consisted of watching over all the vessels which formed part of the auxiliary equipment of the Tabernacle, i.e. אשר יעשה להם, “watching over all that would be done with them or to them.” For instance, seeing to it that the tools enabling the pegs to be firmly implanted in the earth so that the wind could not blow away the carpets forming the roof of the Tabernacle would be in good shape and position.