Today's daf is sponsored by Deborah Aschheim (Weiss) on the occasion of the Bat Mitzvah of her granddaughter Tamar Chava Baumser. "She demonstrates that there are no boundaries to acts of gemulat chasidim."
Today's daf is dedicated by the Hadran Zoom family in honor of Chani Farber and Saar Har-Chen, on the occasion of their wedding. We wish you a new home that will be grounded in the happiness that is promised to one who brings their learning always, as we learned with Chani's mother, Rabbanit Michelle: אַשְׁרִי מִי שֶׁבָּא לְכָאן וְתַלְמוּדוּ בְּיָדו.
If the person who is obligated to take an oath by Torah law is not trustworthy, i.e. if they lied in a previous case or are in the category of those who are exempt from testifying, the obligation to take the oath is placed upon the other person. If one asks a storekeeper to pay their workers and they will pay back the storekeeper later, and the storekeeper claims that he/she paid them and the workers claim they were never paid, each of them takes an oath and the person needs to pay them both. Ben Nanas agrees that the person needs to pay both, but does not allow each side to take an oath as it creates a situation where clearly one side is taking a false oath.
The Mishna lists other cases where there is a disagreement between a storekeeper and a buyer about whether the money was already paid or the item was given to the buyer. Who takes the oath in each case?
Generally, when one holds a deed in hand, they have the upper hand. However, the Mishna mentions cases where the one holding the deed needs to take an oath in order to collect the money.
The Gemara explains why the worker is believed to say he/she didn't get paid for a job performed. However, this halacha is qualified as only applying in a case where the time in which the worker should have been paid hasn't passed yet - once that time passes, there is an assumption that the employer paid the worker.
Shmuel and Rav both hold that the worker can take this oath to get paid only if there were witnesses who saw the worker being hired. If not, the employer can claim he/she never hired the worker at all and therefore is believed by saying the worker was already paid because of a "migo." Rava disagrees with this.