The Mishna on our daf brings the case of two cities that were close enough to one another that someone could establish an eiruv and walk from one to the other. According to Rabbi Yehuda, a person who was heading from one city to the other on Friday afternoon – even if he was called back by his friend and did not reach it – can walk there on Shabbat, as he has established his eiruv by walking. Nevertheless, other people in the city would not be allowed to walk there. Rabbi Meir rules that since he did not clearly state his intention to establish an eiruv in that place, he falls into the proverbial “donkey-camel driver” situation (see 35a-b) and is limited in both directions.
According to Maimonides, the explanation for this case is that the person was sent by the community to be their representative in establishing an eiruv so that they would be able to walk to their neighboring city. Instead of placing food to create the eiruv, he simply walked to the edge of the tehum . Such an eiruv works for him, but the community cannot rely on their messenger’s physical presence to create an eiruv for them.
The Jerusalem Talmud has two explanations for this Mishna, both of which suggest that the person involved was sent as a representative of the community to establish an eiruv between the two cities, and it is his friend who called him back who has a different status than the rest of the city’s inhabitants.
According to the first explanation, the messenger successful established the eiruv for the entire city – except for the individual who called him back. So his friend can continue to walk the normal 2,000 amot around the city, while the rest of the city can walk one way only – towards the neighboring city.
The second explanation understands the case to be when the messenger did not succeed in establishing the eiruv for anyone. The city’s inhabitants cannot walk to the next city, but the friend who was with him succeeded in establishing an eiruv for himself by virtue of his presence, so he is allowed to walk to the next city.