Although the only oaths that we find in the Torah are those that allow a defendant to swear and free himself from a monetary obligation (see Shemot 22:10), nevertheless the Sages of the Mishnah established oaths that would allow a plaintiff to swear and by doing so, to receive payment. These oaths are described in Perek Kol Ha-Nishba’im, the seventh chapter of Masechet Shevu’ot, which begins on today’s daf (=page).
There are a number of categories of people who are nishba ve-notel – who take an oath and collect their claim. One such situation is when there are raglayim la-davar – when there are strong reasons to think that the claim of the plaintiff has merit. Such cases include situations like an employee who claims his wages or a storekeeper whose records show that money is owed to him.
Although the Mishnah lists such cases with the words ve-elu nishba’im ve-notlim – “these are the ones who can take an oath and collect,” Tosafot point out that the list is not exhaustive, as we find other cases where a similar rule applies, e.g. a creditor who comes to collect from the children of the person who owes him money after his death.
Tosafot explain that the cases listed in our Mishnah are only those where the oath was instituted by the Sages for the benefit of the plaintiff, that is to say, cases where he would ordinarily have been unable to collect the money owed to him and the oath instituted by the Sages allows him to collect the money that he is owed. There are other cases of nishba ve-notel where the person should have been able to collect even without an oath, and the institution of an oath was an additional demand made on the plaintiff by the Sages. Such cases of nishba ve-notel are not included in our Mishnah.