Perek ha-Isha Rabba, the tenth chapter of Massekhet Yevamot, began on the previous daf. (It is called ha-Isha Rabba because it is one of several chapters in Massekhet Yevamot that begins with the word ha-Isha – “a woman” – and in order to distinguish it from the others, as the largest perek, or chapter, in the massekhet, it is called rabba – “the large one” or “great one.”) As opposed to the first perakim of the massekhet, which all dealt with questions of yibum when we know that the husband had died, this perek focuses on questionable circumstances.
What if we get word that one spouse has died, but that testimony is later contradicted? Under such circumstances we may find that the alleged widow will marry, even as she is still a married woman. Similarly, the husband may find himself in a forbidden relationship with his wife’s sister, who he married while under the misimpression that his wife had passed away. Even though these marriages may have taken place with the permission of the Jewish courts, under most circumstances, a mistaken ruling by those batei din cannot permit this forbidden relationship.
One circumstance that can lead to this type of situation is when a single witness comes and testifies that the husband is dead and based on this testimony the courts permit the alleged widow to remarry. Ordinarily halakha demands that two witnesses testify in order to clarify a situation. Why is this case different?
Rabbi Zeira explains that mitokh homer she-hekmarta aleha be-sofa, hekaltah aleha ba-tehila – since the court leaves serious consequences if the testimony is found to be untrue, it is willing to be lenient in allowing her to marry. According to the Gemara, this concept is based on a more basic principle of mishum iguna akilu bah rabbanan – that out of concern for the “anchored woman” who is “chained” to a man who we believe to be dead, the Sages were willing to offer her whatever opportunity they could to allow her to resume a normal life.