Shevuot (Oaths) 48 - When Borrower Dies
When a lender dies, the money that he had loaned out belongs to his children. Before collecting, they must take an "oath of heirs," which states that to the best of their knowledge the debt was not repaid.
However, as both Rav and Shmuel have stated, that is only true if the lender died first. If, on the other hand, the borrower died first, then the lender has to take a definite oath that the debt was not repaid. His children cannot take such a definite oath, but only to the best of their knowledge, and it is not sufficient. Thus, if their father now dies, they cannot collect the money at all.
Rabbi Elazar in Israel disagreed, "Just because the lender's children cannot take the same oath as him, must they forfeit their father's debt?"
In practice, the ruling of Rav and Shmuel was followed, but, since there was not a definite decision either way, if a judge ruled in accordance with Rabbi Elazar, his ruling would also stand.
Art: Luigi Nono - A Child's Funeral