As we learned on yesterday’s daf, Beit Hillel believes that the mitzva of yibum does not apply in a case where a man was married to two women – one of whom was forbidden to marry his brother – and he dies without children. In such a case, neither the erva (the woman who was forbidden), nor her rival wife (a tzarah in the language of the Mishna), will become yevamot (widows waiting to be married or released by their brother-in-law).
According to Beit Shammai, however, the tzarah is treated independently and is subject to the rules of yibum and/or halitza as if she had been the only wife of the deceased. The Mishna comments that, their disagreement notwithstanding, the families of Beit Shammai and Beit Hillel continued to marry one another.
One suggestion raised in the Gemara’s attempt to explain why the families were willing to marry one another is that, on a practical level, Beit Shammai accepted Beit Hillel’s rulings, even though they disagreed on a theoretical level. One example presented by the Gemara to prove that Beit Shammai insisted that their position was the correct one was the case of shoket Yehu – Yehu’s trough, which was connected to a regulation-size mikveh via a small opening, and people used it to immerse vessels that had become tameh (ritually defiled).
The Gemara relates that Beit Shammai arranged for the connection between the trough and the mikveh to be widened, since their position is that to be considered a kosher mikveh there must be a large opening between them; Beit Hillel believed that only a small opening – the size of a shfoferet ha-node – was necessary.
The node of a shfoferet ha-node is a bag or bottle made of an entire skin removed from an animal. These skins were used for a variety of purposes, but primarily to store small objects or food. When one was used to store liquids (water, wine or oil, for example) the skin would be removed without making any holes in it, and they would leave the skin of the legs attached, as well. When finished, one of the legs would have a tube – usually a reed – inserted into it, and the liquids would be poured in and out from that small tube.