[If] one sells a house of the houses of walled cities, he may redeem [it] immediately, and he may redeem [it] all twelve months. This is like a kind of interest, but it is not interest. Should the seller die, his son may redeem [it]. Should the buyer die, he may redeem [it] from his son. He counts the year for it only from the time he sold [it] to him; as it says: Until a full year has elapsed for him (Lev. 25:30). When [Scripture] says: full, [it comes] to include the intercalary month. Rabbi says: He must give him a year and its intercalary [days].