Numbers 35:2

Command the children of Israel that they give unto the Levites of the Inheritance of their possession cities to dwell in, for the Levites, as a tribe, received no special territory in the land of Canaan, Numbers 18:20; and ye shall give also unto the Levites suburbs for the cities round about them, meadows, pasture-land for their herds and flocks, fields which could not be sold, but remained the permanent and inalienable property of the Levites, Leviticus 25:34. This does not hold true of the cities themselves, for in these it was only the houses that were given to the Levites, in regard to which the Lord had provided that they could be redeemed at any time after being sold and should always be returned to the original owners or their heirs in the Year of Jubilee, Leviticus 25:32.