Reference for Arakhin 9:5

כֹּל שֶׁהוּא לִפְנִים מִן הַחוֹמָה, הֲרֵי הוּא כְבָתֵּי עָרֵי חוֹמָה, חוּץ מִן הַשָּׂדוֹת. רַבִּי מֵאִיר אוֹמֵר, אַף הַשָּׂדוֹת. בַּיִת הַבָּנוּי בַּחוֹמָה, רַבִּי יְהוּדָה אוֹמֵר, אֵינוֹ כְבָתֵּי עָרֵי חוֹמָה. רַבִּי שִׁמְעוֹן אוֹמֵר, כֹּתֶל הַחִיצוֹן הִיא חוֹמָתוֹ:

Whatever is within the [city] wall is regarded as the houses in a walled city, with the exception of fields. Rabbi Meir says: even fields. A house built into the wall: Rabbi Judah says: it is not considered a house within a walled city. Rabbi Shimon says: its outer wall is regarded as its [city] wall.

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