Taking an oath in a beit din is considered a serious matter, one that cannot be taken lightly. It should be noted that unlike most modern-day courtrooms where the witnesses are asked to take an oath that they are telling the truth, in a beit din we ensure that the witnesses are reliable and are telling the truth in other ways. In a Jewish court an oath is imposed on the plaintiff when evidence demands that he support his claim by means of a serious, weighty statement.
The Mishna (26a) teaches that when the beit din rules that an individual is obligated to take an oath on a specific matter, other issues that are in dispute can also be included in the oath, even if they are matters that ordinarily would not require an oath. The Gemara on our daf discusses this rule, called gilgul shevua – literally, “rolling over”, or extension, of an oath. Ulla teaches that the source for the concept of gilgul shevua is the law of sota. We find that a sota who is required to take an oath that she did not commit adultery listens to the words of the kohen who is officiating at the ceremony and responds “Amen, Amen.” This response is interpreted by the Gemara to include not only her denial of an adulterous relationship with this specific man, but also another man and not only at this time, but at different points in her life, as well.
According to the Rambam, it is not the kohen who initiates the gilgul shevua that requires that the oath include other situations beyond the one that she is accused of, rather he offers the option to the husband to include these, as well. According to the Rosh, however, it is the kohen (or, in our case, the beit din) who may choose to include other issues in an oath, beyond the one that is creating the obligation to take the oath.