צְנָ֥ן וַחֲדָשָׁ֖ה וּמִגְדַּל־גָּֽד׃
Zenan, Hadasa, Migdal-Gad,
English Explanation of Mishnah Eruvin
But if a town belonged to the many and was converted into one belonging to an individual, they may not make an eruv for the entire town unless they excluded from it a section the size of the town of Hadashah in Judea, which contains fifty residents, the words of Rabbi Judah. Rabbi Shimon says: three courtyards each of which contains two houses. Similarly, a town which used to belong to the many and now is acquired by an individual is still treated as a town which belongs to the many. Its status is also not affected by its conversion. Therefore, they may not set up an eruv to allow people to carry in the entire town. Rather they must exclude from the area which participates in the eruv a section the size of the town Hadashah in Judea. “Hadashah” means new, and is mentioned in Joshua 15:37. Here the name of the city is read “midrashically” it is a new city which adds to the old city, sort of an appendage to the older city. In this “New City”, there were 50 residents. According to Rabbi Judah, by excluding an area this size, they may set up an eruv in the rest of the city. Rabbi Shimon disagrees and holds that the excluded part need only be an area the size of three courtyards, each of which has at least two homes. This would probably yield an area slightly smaller than that according to Rabbi Judah’s ruling.