Shavuot page 43. Bava Metzia page 34 and 35, and to a lesser extent, Bava Metzia page 48 and 82

Rav Shach spends a lot of time and effort on the argument between the Ramban and the Ran about a case of a loan where the lender says the pledge was lost, and it was worth half the loan, and the borrower says the pledge was worth 3/4s of the loan. In that case, the Mishna says the lender has to take an oath testifying as to the value of the pledge, and has to pay the last 1/4 of the loan. The Ramban (Nachmanides) asks, "Is it this not a case of when there is a loan, and the lender claims 100, and the borrower says, "50 I admit I owe, and the other fifty I do not know'" in which case, the last fifty does not have to be paid. Rav Shach suggests an answer to this question from Bava Metzia page 34 and 35 where Rav Huna said the lender has to take an oath that the pledge is not in his domain. Rav Shach says after the fact that he has to take an oath, there is no claim of the other side to say, "I do not believe the oath." The problem with this answer is that there is a place in the Rambam (which I will try to find) in which the Rambam says that oath is only in certain cases where there is a great suspicion that the lender might have confiscated the pledge more than in usual cases. Thus, in other cases, why should the borrower believe the lender at all? Let him say, "I will pay back the loan when I get back the pledge." [Besides that, I wonder about this because that oath itself the object of a debate. The problem is the law that the Rambam is bringing here is the Mishna in Shavuot page 43 while the obligation of that oath is the claim of Rav Huna (that Rav Ashi asks on). And even if we agree with it, it is still an argument whether it is from the Torah or derabanan (from the words of the Sages). And if it is derabanan, then how can it affect the law of the Torah which says in a case of "Fifty I admit, and fifty I not know," that he is not obligated?, so it is not a case of where it admits an obligation in part. Rather part of the obligation he says, "I do not know" and the other ¾ he admits he owes.]--------------------------רב שך spends a lot of time and effort on the argument between the רמב''ן and the ר''ן about a case of a loan where the lender says the pledge was lost and was worth half the loan and the borrower says the pledge was worth 3/4s of the loan. In that case the ממשנה says the lender has to take an oath testifying as to the value of the pledge, and has to pay the last 1/4 of the loan. The רמב''ן asks it this not a case of when there is a loan and the lender claims 100, and the borrower says “50 I admit I owe, and the other fifty I do not know”, in which case the last fifty does not have to be paid. רב שך suggests an answer to this question from בבא מציעא page ל''ד and ל''ה where רב הונא said the lender has to take an oath that the pledge is not in his domain. רב שך says after the fact that he has to take an oath, there is no legitimise claim of the other side to sayת "I do not believe the oath." The problem with this answer is that there is a place in the רמב''ם which I will try to find in which the רמב''ם says that oath is only in certain cases where there is a greater suspicion that the lender might have confiscated the pledge than in usual cases. Thus, in other cases, why should the borrower believe the lender at all. Let him say, I will pay back the loan when I get back the pledge. [Besides that, I wonder is that oath itself the object of a debate. The problem is the law that the רמב''ם is bringing here is the משנה in שבועות page 43 while the obligation that oath is the claim ofרב הונא that רב אשי asks on. And even if we agree with it, it is still an argument whether it is from the Torah or דרבנן. And if it is דרבנן, then how can it affect the law of the תורה which says in a case of fifty I admit a fifty I not know," that he is not obligated, so it is not a case o where it admits an obligation in part. Rather Part of the obligation he says I do not know and the other ¾ he admits he owes.]