Arachin, Chapter 9, Mishnah 5. This chapter has been occupied with houses located inside cities surrounded by a wall from the days of Yehoshua. Such a house has its own redemption rule: the seller has a full year in which to buy it back, and once those twelve months pass, the sale becomes permanent. The house does not return to its original owner at the yovel; it stays with the buyer from that point on. Our mishnah now asks a different sort of question: which properties inside such a city actually fall under this halacha?
Everything Within the Wall
The ruling is stated sweepingly. Whatever stands "lifnim min hachoma," on the inner side of the wall, is given the legal standing of "batei arei choma," dwellings belonging to a city that is walled. One category alone is carved out: "chutz min hasadot," fields are set aside.
The mishnah is broadening the category well beyond ordinary dwellings. A bathhouse, an olive press, any built structure that people put to use inside the city, all of these carry the same status as a residence for these purposes.
Where does this come from? The pasuk speaks of a house "asher ba'ir," which is in the city, and it also uses the word bayit. Two conditions emerge from those words. The property must be located within the city, and it must bear some resemblance to a house. A bathhouse and an olive press are structures, so they qualify on both counts. A field satisfies the first condition but not the second, and that is precisely why the mishnah adds chutz min hasadot. An open field bears no similarity whatsoever to a house, so the laws of batei arei choma do not touch it. Everything else inside the wall is included.
Rabbi Meir and the Fields
Rabbi Meir disagrees with that final exclusion: "Af hasadot," even the fields are governed by these halachot.
The Gemara and the Bartenura are careful to define what he means, because Rabbi Meir certainly does not dispute that the pasuk says bayit, and an ordinary field is no house. His case is a specific one: a field that is not ra'uy lizri'ah, land unfit for planting. Picture a rocky patch inside the city from which people would quarry the stone and earth out of the ground and cart it away for construction. Since the very produce of such a field is building material for houses, Rabbi Meir considers it house-like enough to be included in this halacha.
A Dwelling Within the Wall's Thickness
The mishnah turns to a further case: bayit habanuy bachoma, a house constructed inside the city wall itself. The city walls were built extremely thick, thick enough that a dwelling could be set within them. So how do we classify it? Is it outside the city, since it sits in the wall rather than behind it, or does anything contained in the wall count as part of the city?
Rabbi Yehudah rules: "Eino kebatei arei choma." Such a dwelling does not receive that status. In his view it never stood inside the city at all; it is a piece of the fortification itself. The twelve month window, at whose close the seller forfeits his right of redemption for good, therefore has no application to it.
Rabbi Shimon holds otherwise: "Kotel hachitzon hu chomato." The exterior face of that structure serves as the city's fortification. A city's boundary, on his reading, is marked by the continuous surface it presents to the outside, and whatever sits behind that surface, including a dwelling embedded in the wall's breadth, is reckoned as being in the city. The halachot of arei choma consequently govern it.