Even though the Torah doesn’t demand one take an oath if one entirely denies a claim against him/her, the rabbis obligated one to take an oath (shvuat heset). The gemara tries to figure out the difference between an oath that the Torah demands and one that the rabbis instituted. In what cases can a creditor insist that the debtor return the money in front of witnesses and if one did not, then one’s claim that the money was already paid back is ignored completely. Two different versions of Rav Asi are brought as well as two different versions of Shmuel’s opinion are brought. Their opinions are questioned in light of our mishna and explained.