Numbers 7:6

and they brought their offering before the LORD, six covered wagons and twelve oxen; a wagon for every two of the princes, and for each one an ox. They presented them before the tabernacle.

The LORD spoke to Moses, saying,

“Accept these from them, that they may be used in doing the service of the Tent of Meeting; and you shall give them to the Levites, to every man according to his service.”

He gave two wagons and four oxen to the sons of Gershon, according to their service.

He gave four wagons and eight oxen to the sons of Merari, according to their service, under the direction of Ithamar the son of Aaron the priest.

But to the sons of Kohath he gave none, because the service of the sanctuary belonged to them; they carried it on their shoulders.