Commento su Bava Batra 1:5
כּוֹפִין אוֹתוֹ לִבְנוֹת בֵּית שַׁעַר וְדֶלֶת לֶחָצֵר. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר, לֹא כָל הַחֲצֵרוֹת רְאוּיוֹת לְבֵית שָׁעַר. כּוֹפִין אוֹתוֹ לִבְנוֹת לָעִיר חוֹמָה וּדְלָתַיִם וּבְרִיחַ. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר, לֹא כָל הָעֲיָרוֹת רְאוּיוֹת לְחוֹמָה. כַּמָּה יְהֵא בָעִיר וִיהֵא כְאַנְשֵׁי הָעִיר, שְׁנֵים עָשָׂר חֹדֶשׁ. קָנָה בָהּ בֵּית דִּירָה, הֲרֵי הוּא כְאַנְשֵׁי הָעִיר מִיָּד:
Lui [un occupante di un cortile che non desidera aiutare gli altri] è costretto a costruire un cancello per il cortile, [dove la guardia del cancello può sedersi all'ombra e impedire ai passanti di dominio pubblico di guardare nel cortile] e (è costretto a costruire) una porta [per il cancello del cortile]. R. Shimon b. Gamliel dice: Non tutti i cortili richiedono un gate-house. [Un cortile non adiacente al dominio pubblico non richiede un cancello. L'halachah non è conforme a R. Shimon b. Gamliel. Perché anche se non confina con il pubblico dominio, a volte c'è una stampa di persone e convergono nel cortile.] R. Shimon b. Gamliel dice: non tutte le città richiedono un muro. [Una città non vicino al confine del nemico non richiede un muro. L'halachah non è conforme a R. Shimon b. Gamliel. Anche se non è vicino al confine del nemico, richiede un muro, perché talvolta arrivano bande armate.] Per quanto tempo qualcuno deve essere in una città per essere considerato uno dei suoi abitanti [per condividere le responsabilità della comunità]? Dodici mesi. [Ma al giorno d'oggi, che vi è un maggiore movimento, il periodo consueto è di trenta giorni.] Se uno ha acquistato un'abitazione, è immediatamente considerato un abitante della città.
Bartenura on Mishnah Bava Batra
English Explanation of Mishnah Bava Batra
They compel [a resident of the town to contribute to] the building of a wall for the town and double doors and a bolt. Rabban Shimon ben Gamaliel says: “Not every town is fit for a wall.”
How long must a man dwell in a town to count as one of the men of the town? Twelve months. If he has purchased a dwelling place he immediately counts as one of the men of the town.
Mishnah five deals with the obligation of a person who shares a courtyard with another to help in building certain parts of the courtyard. The second half of the mishnah deals with the obligations that residents of a town have to participate in the costs of building the public structures in the town.
Section one teaches that a person who holds joint possession of a courtyard can be compelled to share in the costs of building a gate-house (where a guard would sit and protect the homes attached to the courtyard) and a door. Since these are necessities of a courtyard, one must participate in their cost. Rabban Shimon ben Gamaliel points out that not all courtyards need a gate-house. Assumedly smaller courtyards can be protected without building a gate-house. Therefore, a person would be obligated to help pay for building a gate-house only as long as the courtyard was fit for one.
Section two discusses similar laws with regards to people who live in a town. Just as in modern society people pay taxes in order to pay for the building and upkeep of town property, so too in the times of the Mishnah people had to jointly pay for the building of a wall, double-doors and a bolt to help protect the town. Again Rabban Shimon ben Gamaliel points out that not all towns are fit for walls. If the town was not a one which would usually have a wall, the residents are not obligated to share in its costs.
Finally, section three discusses how long a person must dwell in the town in order to be an official resident and thereby be obligated to pay for building its wall. There are two criteria. First of all, if he dwells in the town for twelve months he is obligated to pay. Second, if he purchases property in the town, he is immediately obligated, even if he doesn’t dwell there.