Jamieson, Fausset and Brown on Leviticus 25:29-31

29-31. if a man sell a dwelling house in a walled city, then he may redeem it within a whole year after it is sold--All sales of houses were subject to the same condition. But there was a difference between the houses of villages (which, being connected with agriculture, were treated as parts of the land) and houses possessed by trading people or foreigners in walled towns, which could only be redeemed within the year after the sale; if not then redeemed, these did not revert to the former owner at the Jubilee.