R' Eliezer says: Two matters are among the lenient [decisions] of Beis Shammai and the stringent [decisions] of Beis Hillel. The blood of a woman who had given birth [and] did not [yet] immerse [in a mikveh]: Beis Shammai say: [It is] like her saliva and her urine. But Beis Hillel say: It generates tumah [both] moist and dry. But [Beis Shammai] concede concerning [a woman] who had given birth in a state of zivah, that [her blood] generates tumah [both] moist and dry.

Four brothers, two of whom were married to two sisters, [and] those who were married to the sisters [both] died, [both of] these [sisters] require chalitzah, but they may not be taken in yibum. And if [the brothers] went ahead and ma-rried [the sis-ters], they must divorce [them]. R' Eliezer says in the name of Beis Shammai: They may keep them; but Beis Hillel say: They must divorce them.