Shevuos chapter 7, mishnah 7. This mishnah opens with a list of cases in which someone coming to collect what is owed to him is required to take an oath. This list is taught in its original place in a mishnah in Maseches Kesubos, in the ninth chapter, and our mishnah establishes: just as an oath is required in those cases, so too orphans coming to collect a debt that belonged to their father - they too are required to take an oath.
This is how the mishnah reads: "Keshem she'amru" - just as the Sages said in Maseches Kesubos:
"Hapogemes kesubasah" - a woman who has already received part of her kesubah but not the full amount. The husband claims that she collected the entire kesubah, and she claims that she collected only part of it, and therefore "lo tipara ela bishvuah" - she does not collect unless she takes an oath.
"Ve'ed echad me'idah shehi peruah" - one witness testifies that she has already been paid, and she says that she has not been paid. True, the document is still in her possession, and that document indicates that she has not been paid, but since there is a witness testifying against her - she does not collect unless she takes an oath.
"Minechasim meshu'badim" - a woman coming to collect her kesubah from property that her husband has already sold to others, and she has a lien on it and can therefore collect from it. Here too she does not collect unless she takes an oath.
"Umin nichsei yesomim" - a widow coming to collect her kesubah from the estate that is now in the hands of the orphans - she does not collect unless she takes an oath.
"Vehanifra'as shelo befanav" - a woman who collects her kesubah when her husband is not present, because he is somewhere else - she does not collect unless she takes an oath.
The law of the orphans:
Just as the Sages said all of these things, "kach hayesomim lo yifra'u ela bishvuah" - orphans coming to collect a debt that was owed to their father, they too do not collect unless they take an oath.
And how do these orphans take an oath? They themselves were not present, and therefore this is the wording of their oath: "Shevuah shelo pikdanu abba, velo amar lanu abba, veshelo matzanu bein shetarosav shel abba sheshtar zeh parua" - our father did not instruct us and did not tell us anything about the debt having already been paid, and we also did not find among his documents anything indicating that this shtar, the contract stating the obligation to pay, was paid.
The Gemara's explanation - who died first:
The Gemara explains that we are dealing with orphans coming to collect from orphans, and from here it follows that the case can be set up in only one way: the lender, who lent the money and whose sons are now coming to collect, died first - during the lifetime of the borrower. In such a scenario, the lender's orphans were already from the outset in a position where they could collect from the borrower, who was still alive.
But if it were the reverse, that the borrower died first: their father, the lender, could only have collected from the orphans by taking an oath, and a person does not bequeath an oath - he cannot transfer to the next generation the right to collect by means of an oath. And since this is the rule, the mishnah must necessarily be dealing with a case where the lender died during the borrower's lifetime, for otherwise the case does not work.
Rabbi Yochanan ben Beroka:
Rabbi Yochanan ben Beroka says: "Afilu nolad haben le'achar misas ha'av, harei zeh nishba venotel" - even if the son who comes to collect with this document was born after his father's passing, and he cannot swear that his father told him nothing, since he never met his father - he still takes an oath and collects. In place of that testimony he swears that he did not find among all the documents that this shtar was paid.
Rabban Shimon ben Gamliel:
Rabban Shimon ben Gamliel says: "Im yesh eidim she'amar ha'av bish'as misaso: shtar zeh eino paru'a - hu notel shelo bishvuah" - if there are witnesses that the father stated at the time of his death that the note had not been repaid, his orphan son collects without taking an oath, since it is as though the oath has already been fulfilled: witnesses testified that the father said precisely what the son would have sworn to, namely that the note had not been repaid. For that reason no oath is needed.
The first Tanna, however, holds that even in this case the son must swear, because we are concerned that the father may have said this only to create the impression that he had potential money owed to him outside and that his son stood to inherit a handsome inheritance, and it is possible that his words were not true. But when he says this to his son, we assume it is the truth, and therefore if the son swears to it he collects.
Summary: In this Mishnah we learned that just as the Sages listed cases in Kesubos in which a woman collects only by taking an oath, so too orphans who come to collect their father's debt swear that their father did not instruct them, did not tell them anything, and that they did not find among his documents that the note had been repaid. We saw the Gemara's conclusion that the lender must have died during the borrower's lifetime, since a person does not bequeath an oath; the view of Rabbi Yochanan ben Beroka that even a son born after his father's death swears and collects; and the dispute between Rabban Shimon ben Gamliel and the first Tanna in a case where there are witnesses to the father's statement at the time of his death.