Eruvin 26B

הא רבי אליעזר, והא רבנן.

This, the Mishnah here, is in accordance with the opinion of R' Eliezer, while that, the other Mishnah, is in accordance with the opinion of the Rabbis.

כשתימצי לומר, לדברי רבי אליעזר: המבטל רשות חצירו ⁠— רשות ביתו ביטל. לרבנן: המבטל רשות חצירו ⁠— רשות ביתו לא ביטל.

Rav Sheshet adds: When you examine the matter closely, you will find that according to the statement of R' Eliezer, one who renounces his authority over his share in the courtyard to the other residents of the courtyard also renounces his authority over his own house. However, according to the opinion of the Rabbis, one who renounces his authority over his share in the courtyard to the other residents does not renounce his authority over his own house to them.

פשיטא!

The Talmud expresses surprise at this comment: But it is obvious that this is the point over which the tanna’im disagree.

אמר רחבה: אנא ורב הונא בר חיננא תרגימנא: לא נצרכא אלא לחמשה ששרוין בחצר אחד ושכח אחד מהן ולא עירב.

The Talmud answers: Raḥava said: Both Rav Huna bar Ḥinnana and I explained: Rav Sheshet’s explanation was necessary only with regard to the case of 5 people who lived in the same courtyard, one of whom forgot to join in an eiruv with the others.

לדברי רבי אליעזר: כשהוא מבטל רשותו, אין צריך לבטל לכל אחד ואחד.

According to the statement of R' Eliezer, when he renounces his authority, he need not renounce it to each and every one of the residents, as we already know that R' Eliezer holds that one who renounces authority does so in a generous manner, renouncing authority not only of his share in the courtyard, but also of his own house. Consequently, if he is required to renounce authority to many people, we assume that he does so even if this is not explicitly stated.