Numbers 35:1-8

Then the LORD spoke to Moses in the plains of Moab by the Jordan [across from] Jericho, saying, “Command the Israelites to give to the Levites cities to live in from the inheritance of their possession; and you shall give to the Levites pasture lands around the cities. The cities shall be theirs to live in; and their pasture lands shall be for their cattle and for their herds and for all their livestock. “The pasture lands around the cities which you shall give to the Levites shall reach from the wall of the city and outward a thousand cubits (1,500 ft.) around. You shall also measure outside the city on the east, south, west, and north sides two thousand cubits (3,000 ft.), with the city in the center. This shall belong to the Levites as pasture lands for the cities. [Among] the cities which you give to the Levites shall be the six cities of refuge, which you shall provide for the one who commits manslaughter to flee to; and in addition to them you shall give forty-two cities [to the Levites]. So you shall give to the Levites forty-eight cities in all, together with their pasture lands. As for the cities which you shall give from the possession of the Israelites, from the larger tribes you shall take many and from the smaller tribes few; each tribe shall give [at least some] of its cities to the Levites in proportion to [the size of] its inheritance which it possesses.”