- המקפיד על עירובו
Rav Yehudah said in the name of Shmuel, המקפיד על עירובו אין עירובו עירוב – If one of the residents of the chatzeir is particular with his portion of the eruv, meaning he does not want anyone to eat the bread that he had given, his eruv is not a valid eruv. The reason for this is that מה שמו? עירוב שמו – What is its name? Eruv is its name. Rashi explains that the shoresh of “eruv” also means “pleasant”, “areiv”, which means that the merger among the residents should be harmonious. Rav Chanina disagrees and says, עירובו עירוב - his eruv is an eruv, אלא שנקרא מאנשי ורדינא – but he is called one of the people of Vardina, who were known for their stinginess.
- עירוב משום קנין או דירה
Shmuel said, עירוב משום קנין – An eruv merges the houses in a chatzeir together by means of an acquisition. And the reason a person cannot purchase a share in an eruv with money, מפני שאינה מצויה בערבי שבתות – because money is not always available erev Shabbos. If one tried making an eruv with money it does not even work בדיעבד because the Chochomim disqualified it because people might come to think that money is the primary method of making an eruv, and if it is not available they might not come to think of making it with bread, and the institution of eruv will fall into disuse and come to be forgotten.
Rabbah says, עירוב משום דירה – An eruv is effective because it effects a residence, meaning it gives all of the residents of the chatzeir a symbolic residence where the bread is placed, even though they do not legally acquire a share of that house.
There are three practical differences between them. According to Shmuel, a kli can be used since it is a viable way to make a kinyan but according to Rabbah it cannot since people identify their residence with their food, not utensils. According to Rabbah, the food can be worth less than a shaveh perutah but according to Shmuel it cannot. According to Rabbah, a child can collect the food for the eruv, but according Shmuel he cannot since he is not old enough to make an acquisition.
- מי שבא בדרך וחשכה לו
The next Mishnah states, מי שבא בדרך וחשכה לו – One who was traveling erev Shabbos and it became dark and he knew of a landmark such as a tree or a fence which was within two thousand amos of both his house and his present location, and said, שביתתי תחתיו – my residence is underneath it, לא אמר כלום – he has said nothing. The Gemara on Daf 50a will explain the reason for this. The Gemara brings a machlokes Rav and Shmuel whether לא אמר כלום means that he has no makom shevisa even in his current location and cannot travel to the tree, or it means that he cannot travel home but he can still travel to the tree.
