Leviticus 25:29-31

A dwelling-house in a walled city Here the law makes a great difference between houses in walled cities and houses in the country. The former, if sold, were either to be redeemed within a year, or else not at all, but were to be the property of the purchaser for ever; whereas, houses in the villages which had no walls round them were to be counted as the fields of the country That is, they were to fall under the same law with the lands to which they were an appendage, and for the management of which they were necessary: they might be redeemed at any time. The following seem to be the chief reasons of this distinction: 1st, There was no danger of confusion in tribes or families by the final alienation of houses in cities, as tribes and families were not distinguished by them as they were by those in the country that were annexed to their lands, and therefore to be considered as a part of their inheritance. 2d, The seller had a greater property in houses than in lands, as being commonly built at the owner's cost, and therefore a fuller power is granted him to dispose of them. 3d, God would hereby encourage persons to buy and possess houses in cities, as the frequency and populousness of them was a great strength, honour, and advantage to the whole land.