As we learned on yesterday’s daf, the Mishna (76b) notes that the nullification of a neder – hafarat nedarim – taken by a woman by her father or her husband, can be done on. Our Gemara brings a Mishna from Massekhet (157a) that reiterates this rule, adding that hatarat nedarim – annulment of a vow by a Jewish court or Rabbi – is only performed on Shabbat if it is a neder that affects Shabbat itself. Hafarat nedarim can only be done on the day that the father or husband hears of the neder, so if it is limited only to nedarim that are connected to Shabbat, then the opportunity to do hafarat nedarim would be lost. This is not the case with regard to hatarat nedarim, which has no such limits. The Gemara points out that according to the opinion in the Mishna that hafarat nedarim can be done for the 24 hours following the neder, if there would be time to do hafarat nedarim after Shabbat then we would also limit hafarat nedarim on Shabbat only to those cases where the neder interferes with Shabbat.
Which rule of Shabbat is it that would limit the types of nedarim that can be annulled on that day?
According to the Ran, since hatarat nedarim appears to be a court decision, we would prefer to avoid doing it on Shabbat. The Ran adds an idea that is found in the Talmud Yerushalmi – that since there is no limitation of the times that a neder might be annulled by the courts, there is no pressing need to do it on Shabbat, so we recommend doing it after Shabbat is over.
The Rambam appears to connect this rule with the words of the prophet that prohibit memtzo heftzekhah ve-daber davar, which forbids speaking about weekday matters on Shabbat (see Yeshayahu 58:13). Thus on, only things that are tzorkhei shamayim – heavenly things – like issues essential for Shabbat, are discussed.