Rashi on Numbers 3:26/רש"י על במדבר ג׳:כ״ו

1ואת מיתריו AND THE CORDS OF IT — This means: those of “the dwelling” (the lower curtains) and of “the tent” (the upper curtains), and not those of the enclosure (חצר) mentioned in this verse [although some of these are stated in Numbers 4:26 to be in charge of the Gershonites].