דאי דרב קשיא דרב אדרב בתרתי דאמר רב ירמיה בר אבא אמר רב מבוי שנפרץ במלואו לחצר ונפרצה חצר כנגדו חצר מותרת ומבוי אסור ואמאי ליהוי כמבוי שכלה לרחבה
For if it is a ruling of Rav, the apparent contradiction between one statement of Rav and another statement of Rav poses a difficulty in two ways. The first is with regard to the fact that this alleyway opens into the public domain on two opposite sides, and the second is based on that which Rav Yirmeya bar Abba said that Rav said: If an alleyway was breached along the entire length of its back wall into a courtyard, and likewise the courtyard was breached opposite it into the public domain, it is permitted to carry in the courtyard, and it is prohibited to carry in the alleyway, since this alleyway is now open on two opposite sides to the public domain. Why should this be the ruling? In this case, let it be like an alleyway that terminates in a backyard, where Rav Yehuda ruled that nothing further is needed to permit carrying.
אמר ליה אנא לא ידענא עובדא הוה בדורא דרעותא מבוי שכלה לרחבה הוה ואתא לקמיה דרב יהודה ולא אצרכיה ולא מידי ואי קשיא משמיה דרב תיהוי משמיה דשמואל ולא קשיא מידי
Rav Yosef said to Abaye: I do not know in accordance with which of his teachers Rav Yehuda issued this ruling. All I know is that there was an incident in a shepherds’ village where an alleyway terminated in a backyard, and the matter came before Rav Yehuda for a ruling, and he did not require anything to render it permitted to carry in the alleyway. And if, as you say, it is difficult if we say that he issued his ruling in the name of Rav, let it be suggested that he issued it in the name of his other teacher, Shmuel, and then there will be no difficulty.
השתא דאמר ליה רב ששת לרב שמואל בר אבא ואמרי ליה לרב יוסף בר אבא אסברא לך כאן שעירבו כאן שלא עירבו
The Gemara comments: Now that Rav Sheshet said to Rav Shmuel bar Abba, and some say that he said to Rav Yosef bar Abba: I will explain to you Rav’s statement with regard to an alleyway that was breached along the entire length of its back wall into a courtyard. One must make a distinction based on the nature of the case: Here it is referring to a case where the residents of the courtyard established an eiruv together. In that case, Rav permits carrying in the alleyway and is not concerned with the breach into the courtyard, as the courtyard and the alleyway are treated as a single domain. There it is referring to a case where the residents did not establish an eiruv together. In that case, Rav prohibits carrying in the alleyway, because the alleyway now has new residents, i.e., the residents of the courtyard, who did not participate in the eiruv, and they prevent the residents of the alleyway from carrying.
דרב אדרב נמי לא קשיא כאן שעירבו בני חצר עם בני מבוי כאן שלא עירבו
Consequently, it can be said that Rav Yehuda’s statement with regard to an alleyway that terminates in a backyard is in accordance with the opinion of Rav, as the apparent contradiction between one statement of Rav and another statement of Rav also poses no difficulty. Here, where Rav Yehuda permits carrying in an alleyway that terminates in a backyard, he is referring to a case where the residents of the courtyard and the residents of the alleyway established a joint eiruv, whereas here, where Rav prohibits carrying in an alleyway that was breached along the entire length of its back wall into a courtyard, he is referring to a case where the residents of the courtyard and the residents of the alleyway did not establish a joint eiruv.