Chapter 4, Mishna 4
Does an object owned by a non-Jew at twilight on Friday acquire its own Shabbos “dwelling” and boundary, limiting how far it can be carried by a Jew on Shabbos? R’ Yochanan says yes. Rava apparently hadn’t heard or thought about this ruling when he permitted the residents of Mechoza to acquire rams from non-Jews in Mavrachta on Shabbos. R’ Hiyya ruled that a water-filled ditch on the edge between two Shabbos boundaries requires an iron partition in order to permit drawing water and carrying away to the person’s own boundary. Rabbi Yosei the son of Rabbi Hanina laughed at R’ Hiyya’s ruling. Why? How do we know that a person’s “place” encompasses 4 cubits? How do we measure those cubits for a very large person?