Sa’if 16, Mechaber: The plaintiff alleges he lent a maneh to the borrower who has since died. The alleged loan is undocumented. So he sues the heir of the borrower for the return of the loan. The heir responds that he knows nothing about the loan, even though there are witnesses who do. Or the heir responds that he does not know whether his father repaid the money or not. Or the heir responds that he knows his father owed fifty dinarim but does not know about the other fifty.
In all these cases, the heir is exempt from payment without having to take the Shevuat Hayorshim, the oath of heirs. However, the plaintiff may ask the court to warn the heir that if he is lying, he will be subject to excommunication. If, however, the heir said my father owed you fifty dinarim but no more than that, thereby admitting his father borrowed fifty dinarim and denying he owed the other fifty, he must take the Modeh Bemiktzat Torah oath of partial admission just like anyone else who admits part of the claim and denies the rest.
Ner Eyal: The rule in Sa’if 12, that one who cannot swear must pay, applies to the debtor himself but not to his heirs. The rationale behind this rule is that a person ought to know whether he owes money. But this rationale does not apply to his heirs. They cannot be expected to be as familiar with the business affairs of their father as they are about their own.
Furthermore, even if the heir knows of the loan or even if witnesses can testify that their father borrowed the money from the plaintiff, it is always possible that their deceased father paid the loan back. The court is concerned the plaintiff might be exploiting the heir’s ignorance of his father’s business affairs and is trying to get paid a second time. Accordingly the rule of “one who cannot swear must pay” does not generally apply to the heirs of the debtor. However, if instead of pleading ignorance the heir admits his father owed fifty but denies the other fifty, he is then demonstrating a level of knowledge about his father’s affairs commensurate with his father and he must take the Modeh Bemiktzat oath of partial admission.
The Shevuat Hayorshim oath of heirs referred to in this Sa’if is the oath that heirs must take when they bring a claim to collect what they allege is owed to their deceased father. They must swear that they did not find any evidence that the loan their father made was repaid. But they are not obliged to take this oath when they are defendants.
The rule is that the heir of a debtor who is sued by the alleged creditor of his father, but who denies that his father owed money, is exempt from taking any oath. He is exempt from taking the Shevuat Heiset oath of denial his father would have had to take had he been alive. This is because the oath of denial was only instituted for the defendant himself but not for his heir. And as explained, he is also exempt from taking the oath of heirs.