If five groups spent the Sabbath in one mansion — Beis Shammai say: An eruv for each group. But Beis Hillel say: One eruv for all of them. They agree, however, that when some of them are quartered in rooms or upper stories, they need an eruv for each group.

Brothers or partners who eat at their father’s table, but who sleep in their own homes, need an eruv for each one. Therefore, if one of them forgot to contribute to the eruv, he must nullify his rights. When is this so? When they bring their eruv to another place; but if the eruv was brought to them, or there are no other residents in the courtyard, they need not contribute to the eruv.