Eruvin 73A

מקום פיתא, ושמואל אמר: מקום לינה.

The place where he eats his bread, and Shmuel said: His place of sleep.

מיתיבי: הרועים, והקייצין והבורגנין ושומרי פירות, בזמן שדרכן ללין בעיר ⁠— הרי הן כאנשי העיר. בזמן שדרכן ללין בשדה ⁠— יש להם אלפים לכל רוח!

The Talmud raises an objection to Rav’s opinion from a baraita: With regard to shepherds; fig watchmen, who guard figs spread out in the field; guardsmen who sit in small guardhouses; and produce watchmen; when they customarily sleep in the city in addition to eating there, they are like the residents of the city with regard to their Shabbat limit, even though they were in the field when Shabbat began. However, when they customarily sleep in the field, even though they eat in the town, they have only 2,000 cubits in each direction from the places where they sleep. This seems to contradict the opinion of Rav, who maintains that a person’s place of residence is determined by where he eats, not by where he sleeps.

התם אנן סהדי דאי ממטו להו ריפתא התם, טפי ניחא להו.

The Talmud answers: There, in the case of the people in the field, we are witnesses, i.e., it is clearly evident, that if people would bring them bread there, to the place where they sleep, it would be more convenient for them. Fundamentally, however, a person’s residence place is determined by where he eats, rather than where he sleeps.

אמר רב יוסף: לא שמיע לי הא שמעתא. אמר ליה אביי: את אמרת ניהלן, ואהא אמרת ניהלן: האחין שהיו אוכלין על שלחן אביהן, וישנים בבתיהן ⁠— צריכין עירוב לכל אחד ואחד. ואמרינן לך: שמע מינה מקום לינה גורם. ואמרת לן עלה, אמר רב יהודה אמר רב: במקבלי פרס שנו.

Rav Yosef said: I have not heard this halakha stated by Rav. An illness had caused Rav Yosef to forget his studies. His student, Abaye, said to him: You yourself said it to us, and it was with regard to this that you said it to us: With regard to brothers who were eating at their father’s table and sleeping in their own houses in the same courtyard, a separate contribution to the eiruv is required for each and every one of them. And we said to you: Can one learn from here that a person’s place of sleep determines the location of his Shabbat residence? And you said to us in this regard that Rav Yehuda said that Rav said: They taught this Mishnah with regard to brothers who receive a portion from their father and are therefore considered as though they eat at his table, whereas in actual fact they eat their meals in their own homes.