The Mishna on our daf returns to the subject of eiruvei hatzeirot, which permit people to carry within a closed area on Shabbat. The discussion revolves around several independent groups of people who are staying in a large hall – a teraklin – and subdivide it by putting up partitions between them. Each partitioned room had a separate entrance to a courtyard that was shared with other houses. In the original Latin, a teraklin was a room that contained three couches on which people reclined, but its meaning later expanded to mean any large room for guests.
Beit Shammai say: An eiruv is required for each and every group, i.e., each group must contribute separately to the eiruv of the courtyard, as each is considered a different house. And Beit Hillel say: One eiruv suffices for all of them, as the partitions do not render the different sections separate houses.
In clarifying what types of partitions the Mishna is discussing, a baraita is quoted in the name of Rabbi Yehuda Hasabbar [“the keen”], who teaches that the disagreement between Beit Shammai and Beit Hillel is only in a case where the partitions do not reach the ceiling. If the partitions do reach the ceiling, then they are considered full-fledged walls, and even Beit Hillel would agree that the people are in separate “houses” and would need to contribute to the eiruv individually.
Rashi explains that Rabbi Yehuda Hasabbar was called “hasabbar” because his sevara – his reasoning – was very sharp. Tosafot, however, are inclined to accept one of the variant readings of his name, either “ha-Sabakh”, because he professionally made Sevakhot – a type of netting used in women’s hair covering – or “ha-Sakkakh” because he was from the city of Sekhakha. Rabbi Yaakov Emden, in his commentary of the Gemara suggests that Tosafot was surprised by the suggestion that only one of the tannaim would be singled out to receive the approbation “hasabbar” due to his sharpness.
As far as the halakha is concerned, the discussion of the Mishna only applies when the groups came for a temporary stay. If these partitioned areas were their permanent homes, they would certainly need an eiruv, even if the partitions did not reach the ceiling. On the other hand, if they were guests of the owner of the house just for they would not need an eiruv at all.