Arachin, Chapter 9, Mishnah 8, the final mishnah of the masechet. Until now the chapter has dealt with fields and dwellings, with what can be bought back and within what span of time. The mishnah now takes up a category all its own: a home belonging to a Levi that stands inside a city with a wall, along with the consecrated limits that ringed every Levite city.
Why the Levite cities are different
At the chalukat ha'aretz, the apportioning of the land among the tribes after Bnei Yisrael came into Eretz Yisrael, two groups were left without a tribal territory: the kohanim and the levi'im. Their share came from the others, for the remaining tribes were commanded to designate a set number of cities within their own allotments as places where the kohanim and the levi'im would live.
An earlier mishnah taught the rule for a dwelling inside a walled city: the seller has twelve months from the day of sale in which to reclaim it, and once those twelve months pass the purchaser holds it permanently. That limit, however, applies to cities belonging to Yisraelim. Should a kohen or a Levi sell a dwelling that stands in one of the arei Levi'im, his power to reclaim it never expires, and the sale can be undone even long after the year is over. Our mishnah now asks about the crossed cases: a Yisrael who holds property inside an ir Levi'im, and a Levi who holds property inside a city of Yisraelim.
A Yisrael in a Levite city
"Yisrael sheyarash avi imo Levi": a Yisrael who received an inheritance from his maternal grandfather, a Levi. Trace the sequence of events. That grandfather owned a dwelling in one of the arei Levi'im. He died leaving no son, only a daughter, so the property came to her. Her husband was a Yisrael, and a son was born to the couple. When she died the dwelling passed to that son, whose standing follows his father, making him a Yisrael. The upshot is a Yisrael holding title to a home inside a Levite city.
"Eino goel kaseder hazeh": he does not redeem according to this arrangement. The privilege of perpetual redemption belongs to the house of a Levi. Here the owner is not a Levi, so the house loses that standing and reverts to the ordinary rule of a walled city: one year to redeem, and no more.
A Levi in a city of Yisraelim
"Vechen Levi sheyarash et avi imo Yisrael", and likewise a Levi who received an inheritance from his mother's father, a Yisrael, "eino goel kaseder hazeh." The mirror image produces the identical outcome. This Levi now owns a dwelling that sits in a walled city of Yisraelim. The man himself is indeed a Levi, but the building does not stand within an ir Levi'im, and so the extended right of buying it back does not attach to it. Its redemption runs on the ordinary twelve month clock.
"Shene'emar ki batei arei haLevi'im": the pasuk speaks of dwellings that stand in Levite cities, and from this Rebbi derives "ad sheyehe Levi ube'arei Levi'im", that the two features must coincide: the owner has to be a Levi, and the building has to be located among the arei Levi'im. "Divrei Rebbi": such is Rebbi's opinion.
"Vachachamim omrim": the Sages take a different view. Their reading turns on one factor only, the site. Any dwelling situated within an ir Levi'im carries the unlimited right of redemption, no matter whose name is on it, and so even a Yisrael who came into such a property by inheritance and afterward sold it may take it back once the twelve months have run out. "Ein hadevarim amurim ela be'arei haLevi'im", the halachah is stated with respect to the location alone. Such is the machloket between Rebbi and the Chachamim.
The open space around the city
Every city given to the levi'im came with a surrounding belt of two thousand amot. That belt was divided in two. The inner thousand amot of the radius, the migrash, was to be left clear and unplanted. The outer thousand amot was set aside as sadeh, field land meant for planting, as the mishnah goes on to discuss. On the level of de'oraita this framework governs the cities of the levi'im, and on the level of deRabbanan the Sages extended it to other cities as well, cities with no connection to the levi'im at all.
"Ein osim sadeh migrash": the outer thousand amot, whose purpose is planting, may not be stripped bare and reclassified as migrash, "velo migrash sadeh", and the cleared belt may not be sown and turned into farmland. "Velo migrash ir": the open belt may not be built up with homes and absorbed into the city, "velo ir migrash", and the city may not be reduced to open belt by pulling down homes at its edge in order to widen the clearing.
Each of the three zones has a place fixed for it: the ir occupies its own area, the migrash its own, and the field land its own, and no zone may swallow up its neighbor. Where the arei Levi'im are concerned this is a Torah law. The Sages afterward legislated the same arrangement as a takanah for every city, Levite or not.
Rabbi Eliezer: cities of Yisrael are treated more flexibly
"Amar Rabbi Eliezer": Rabbi Eliezer qualifies the ruling. "Bameh devarim amurim", where does this inflexible law apply, the law forbidding any shift among farmland, open belt and built up city? "Be'arei haLevi'im", to the Levite cities alone. "Aval be'arei Yisrael": in cities belonging to Yisrael, certain conversions are indeed permitted.
"Osim sadeh migrash": farmland may be cleared and reclassified as open space, since an open expanse enhances the appearance of the city. "Velo migrash sadeh": but open space may not be sown and turned into farmland, because that diminishes that appearance.
"Migrash ir": the open belt may be built upon and drawn into the city, because that brings in more residents, and a larger population outweighs even the city's appearance. "Velo ir migrash": homes may not be demolished so as to convert city into open belt, since fewer houses mean fewer people dwelling there. The reason given is "kedei shelo yacharivu", that ruin should not come upon "arei Yisrael", the cities of the land. Change may move in one direction only: toward additional homes, additional Jewish households and a larger settled population in Eretz Yisrael.
Perpetual sale and perpetual redemption
"Hakohanim vehaLevi'im mochrim le'olam": a kohen or a Levi may sell his field in a Levite city whenever he wishes, the two years immediately before Yovel included. A Yisrael's sdei achuzah, his ancestral field, is subject to a different rule: it may not be sold during those closing two years.
"Vego'alim le'olam": their power of redemption is equally unrestricted. Suppose a Levi or a kohen sold a field situated in an ir Levi'im; he need not wait, and may buy it back already during the opening two years of the sale. And if what he sold was a dwelling in one of the Levite cities, he may reclaim it once the twelve months have elapsed. Everyone else is bound by tighter terms: a field only from the third year onward, and a dwelling in a walled town only within the first twelve months.
"Shene'emar ge'ulat olam tiheyeh laLevi'im": as the verse states, an eternal redemption shall be for the levi'im, teaching that the levi'im may redeem at any time.
Hadran alach Masechet Arachin.