Arachin, Chapter 9, Mishnah 3. Having dealt with the sale and redemption of a sdeh achuzah, an ancestral field, the Mishnah now moves to a different kind of property: houses in Eretz Yisrael. Houses, like ancestral fields, can be bought back by their original owner, but the rules governing that redemption follow their own pattern and differ from the laws of the ancestral field.
There are two categories of homes to keep in mind: a house located within a walled city (arei chomah) and a house located in an unwalled, open city. The halachah depends entirely on which of the two we are discussing. The next four mishnayot are devoted to the first category, houses in walled cities.
Immediate Redemption, but Only for Twelve Months
The Mishnah's case is a person who sells a house standing among the dwellings of a city encircled by a wall: "hamocher bayit b'batei arei chomah." Of such a seller the Mishnah rules "harei zeh go'el miyad" - the door to buying his home back is open to him immediately. The owner of an ancestral field had to let two years pass before he could reclaim it; here the power to redeem exists from the very day the sale is made.
How long does that power last? "V'go'el," he redeems, and he may act at any point within the twelve months that follow, "kol shneim asar chodesh." That period, though, is a hard limit. Once the twelfth month runs out, ownership settles permanently on the purchaser and the man who sold the house loses his claim forever. Such homes are not restored to their first owners when Yovel arrives, so a seller who let the year slip by without acting has no further remedy: the property is the purchaser's for all time.
Something That Resembles Interest
The Mishnah then pauses to characterize the arrangement. It has the flavor of interest, "k'min ribit," and yet, the Mishnah adds, "v'eina ribit," it is no interest at all. The halachah is that a seller who reclaims his house within the year hands back precisely the sum he was paid. If the sale price was one hundred dinar, one hundred dinar is what he returns, not a coin more and not a coin less.
On the surface this has the appearance of a loan with interest. The buyer's money is returned to him in full, as a lender's principal would be, and in the meantime he has lived in the house for the better part of a year without paying anything for the privilege. Nevertheless the Mishnah teaches: "v'eina ribit," it is not ribit. It carries the look of interest, but the Torah's own arrangement of redemption is not a prohibited loan.
When the Seller or the Buyer Dies
What happens if death intervenes during that year? Should the seller pass away, "met hamocher," the Mishnah rules "yig'al bno": his son may carry out the redemption. The privilege of buying the house back is itself part of the estate, and the heir takes up the position his father held.
And should the purchaser be the one who dies, "met haloke'ach," the house passes into the hands of his heir, and the Mishnah teaches "yig'al miyad bno": the man who sold it redeems it directly from that heir.
Counting the Year from the Original Sale
"Eino moneh lo shanah" - the twelve months are reckoned, says the Mishnah, "ela misha'ah shemachar lo," only from the hour of the original transaction. Should the purchaser turn around and sell the property to a third party, the seller's year does not begin afresh. A second sale does not restart the count; it runs from the day the house first left its owner's hands.
This is drawn from the pasuk "ad m'lot lo shanah temimah," until the completion of a year for him. The Mishnah presses on the word "lo," for him, which points to the man who sold the house. The measurement therefore begins with his own sale, regardless of how many hands the property passed through afterward.
What Does Temimah Add?
"Uk'shehu omer temimah, l'havi chodesh ha'ibur": the Torah's additional word, "temimah," a whole year, comes to bring in the thirteenth month that an intercalated year contains. Where the sale took place in a year to which a month had been added, the seller's period of redemption stretches across thirteen months, since that additional month belongs to the year itself. On this reading, "temimah" is teaching a halachah that matters only in an intercalated year and contributes nothing in a regular one.
Rebbi reads the word differently. In his view the Torah "yiten lo shanah v'ibura," granting the seller a year together with its supplement, and this holds in every year, not merely an intercalated one. The supplement he has in mind is the stretch of some eleven days by which the lunar year falls short of the solar year of roughly 365 days, the year of the calendar we are all used to. For Rebbi, then, "temimah" secures the seller a complete 365 days in which to reclaim his house, in an ordinary year no less than in a leap year.