כליו של אדם קונה לו בכל מקום חוץ מרה"ר ורבי יוחנן ור"ש בן לקיש דאמרי תרוייהו אפילו ברה"ר
A person’s vessels effect acquisition of any item placed inside them for him, in any place in which they are situated, except for the public domain. And Rabbi Yoḥanan and Rabbi Shimon ben Lakish both say: Even in the public domain, one’s vessels effect acquisition of items placed in them.
אמר רב פפא לא פליגי כאן ברה"ר כאן בסימטא ואמאי קרו לה רה"ר שאין רשות היחיד
Rav Pappa said: These amora’im do not disagree: Here, when Rav and Shmuel state that one’s vessel does not effect acquisition for him, they are speaking of a vessel placed in the public domain; there, when Rabbi Yoḥanan and Reish Lakish state that his vessel effects acquisition on his behalf, they are referring to a vessel located in an alleyway. And why do they call an alleyway the public domain? The reason is that an alleyway is not a private domain.
ה"נ מסתברא דא"ר אבהו א"ר יוחנן כליו של אדם קונה לו בכל מקום שיש לו רשות להניחו יש לו רשות אין אין לו רשות לא ש"מ
The Gemara points out: So, too, it is reasonable to interpret Rabbi Yoḥanan’s statement in this manner, as Rabbi Abbahu says that Rabbi Yoḥanan says: A person’s vessels effect acquisition for him in any place where he has permission to keep them. It can be inferred from here: In a location where he has permission to keep them, yes, his vessels effect acquisition for him. But in a place where he does not have permission to keep his vessels, they do not effect acquisition for him, and one has permission to keep his vessels in an alleyway but not in the public domain. The Gemara affirms: Conclude from this statement that when Rabbi Yoḥanan referred to the public domain he meant an alleyway.
תא שמע ארבע מדות במוכרין עד שלא נתמלאה מדה למוכר משנתמלאה מדה ללוקח בד"א במדה שאינה של שניהן אבל אם היתה מדה של אחד מהן ראשון ראשון קנה
The Gemara suggests: Come and hear a difficulty from a baraita: There are four cases with regard to sellers, i.e., four methods through which merchandise is acquired. When the seller measures merchandise for the buyer, before the measuring vessel has been filled the merchandise in the vessel still belongs to the seller and he can change his mind and cancel the sale. Once the measuring vessel has been filled the merchandise belongs to the buyer. In what case is this statement said? It is said when the seller measures with a measuring vessel that does not belong to either of them. But if the measuring vessel belonged to one of them, the buyer acquires the items of sale one by one as they are placed in the measuring vessel.
במה דברים אמורים ברה"ר ובחצר שאינה של שניהן אבל ברשות מוכר לא קנה עד שיגביהנה או עד שיוציאנה מרשותו ברשות לוקח כיון שקבל עליו מוכר קנה לוקח ברשות הלה המופקדים אצלו לא קנה עד שיקבל עליו או עד שישכור את מקומן
In what case is this statement said? It is said when the seller measures the items in the public domain or in a courtyard that does not belong to either of them. But if it happens in the domain of the seller, the buyer does not acquire the merchandise until he lifts the measuring vessel or until he moves it out of the domain of the seller. If it is in the domain of the buyer, once the seller accepts upon himself to sell, the buyer acquires it. If the merchandise is located in the domain of this individual with whom it had been deposited, the buyer does not acquire it until the bailee accepts upon himself to designate a place where the merchandise is to be stored for the buyer, or until the buyer rents from the bailee the place where the merchandise is situated.
קתני מיהא ברשות הרבים ובחצר שאינה של שניהן
In any event, this baraita teaches with regard to a transaction in the public domain or in a courtyard that does not belong to either of them that if the measuring vessel belonged to one of them, the buyer acquires the items of sale one by one as they are placed in the vessel.