Numbers 7:7

7:7 He gave two carts and four oxen to the Gershonites, as their service required;

Numbers 7:9

7:9 But to the Kohathites he gave none, because the service of the holy things, which they carried ¹  on their shoulders, was their responsibility. ² 

Numbers 20:21

20:21 So Edom refused to give Israel passage through his border; therefore Israel turned away from him.

¹ tn The verb is the imperfect tense, but it describes their customary activity – they had to carry, they used to carry.

² tn Heb “upon them,” meaning “their duty.”