Eruvin 45B

ובלבד שלא יוציא זה מתוך שלו לתוך של חברו.

provided that the one does not carry anything from his 4-cubit limit into that of his fellow.

היו שלשה והאמצעי מובלע ביניהן ⁠— הוא מותר עמהן, והן מותרין עמו, ושנים החיצונים אסורין זה עם זה.

With regard to a case where there were 3 people in this situation, and certain parts of the 4 cubits of the middle one were subsumed within the respective limits of each of the others, so that he shared a certain area with each of them, he is permitted to eat with either of them, and they are both permitted to eat with him; but the two outer ones are forbidden to eat with each other, since they share no common area.

אמר רבי שמעון: למה הדבר דומה ⁠— לשלש חצירות הפתוחות זו לזו, ופתוחות לרשות הרבים. עירבו שתים עם האמצעית ⁠— היא מותרת עמהן והם מותרות עמה, ושתים החיצונות אסורות זו עם זו.

R' Shimon said: To what is this comparable? It is like 3 courtyards that open into one another, and also open into a public domain. If the two outer courtyards established an eiruv with the middle one, the middle one is permitted to carry to the two outer ones, and they are permitted to carry to it, but the two outer courtyards are prohibited to carry from one to the other, as they did not establish an eiruv with one another.

גמ׳ בעי רבא: מאי קסבר רבי יוחנן בן נורי? מסבר קא סבר: חפצי הפקר קונין שביתה.

Talmud: Rava raised a dilemma: What does R' Yoḥanan ben Nuri hold? Does he hold that ownerless objects acquire residence for Shabbat, i.e., even an article that does not belong to anyone acquires residence at the onset of Shabbat and can therefore be carried 2,000 cubits in each direction?

ובדין הוא דליפלוג בכלים. והא דקמיפלגי באדם ⁠— להודיעך כוחן דרבנן, דאף על גב דאיכא למימר: הואיל וניעור קנה, ישן נמי קנה, קא משמע לן דלא.

And according to this understanding, R' Yoḥanan ben Nuri should by right have disagreed with the Rabbis even about utensils that were left in the field, i.e., that according to the opinion of R' Yoḥanan ben Nuri, ownerless utensils can be moved 2,000 cubits in each direction. And the reason that they disagreed about a person is to convey the far-reaching nature of the stringent ruling of the Rabbis, that although there is room to say: Since a person who is awake acquires for himself 2,000 cubits, he also acquires them if he is sleeping, the Mishnah nonetheless teaches us that the Rabbis did not accept this argument, and this is why the dispute is taught specifically with respect to a person.