Shevuos, Chapter 7, Mishnah 1. The Mishnah before us presents an entire list of rabbinic oaths, in which the one who swears collects his claim. This Mishnah enumerates them all and spells out the laws of the first of them, while the rest will be discussed in the Mishnayos that follow.
The Mishnah opens: "Kol hanishba'in shebaTorah nishba'in velo meshalmin" - all the oaths that the Torah created are built on a single pattern: the defendant swears that his words are true, and by force of his oath he is not required to pay the money claimed from him. So it is in every form of oath from the Torah:
Modeh bemiktzas - a defendant who admits to part of the claim.
Ed echad - a single witness who testifies against him.
Shevuas hashomrim - one in whose hands an object was deposited for safekeeping, and something happened to the object.
In all of these cases the one who swears is exempt from payment.
"Ve'elu nishba'in venotlin":
Now the Mishnah enumerates the cases that are rabbinic - cases in which the Sages instituted an enactment that a person swears and on the basis of his oath he collects. We will mention them briefly, and afterwards we will go into the details:
"HaSachir" - a hired worker, and the details of the case will be explained in the Mishnah itself.
"VehaNigzal" - one from whom an object was stolen.
"VehaNechbal" - one who suffered a physical injury.
"Ushekenegdo chashud al hashevuah" - where the opposing litigant was supposed by Torah law to swear, but he is suspect because of his character that he would lie in his oath, and he is not believed. In such a case the claimant can collect on the basis of his own oath.
"Vehachenvani al pinkaso" - a shopkeeper who recorded something in his ledger, in his account book. The details of the case will be explained a few Mishnayos from here.
"HaSachir keitzad?"
What exactly is the case of a hired worker? The worker says to the employer: "Ten li sechari sheyesh li beyadecha" - give me my wages that are in your hand and that you owe me. The employer answers: "Nasati" - I already paid you. And the worker says that he never collected. On the basis of this claim he may swear and collect.
The Gemara explains the reason for the enactment: the employer is preoccupied at that time with his many workers, and therefore it is hard for him to remember to whom he gave money and to whom he did not. The worker, by contrast, is one person, and he invested his sweat and his tears in this work - and therefore he is keenly aware of the question whether he received his wages or not. For that reason he is believed and is allowed to collect.
The Gemara, however, qualifies this: this law applies only up until the time when the employer is obligated to pay the worker. Once that time has arrived - daybreak or sunset, depending on when the worker was hired - and the time has passed at which the employer, had he not paid, would have transgressed the Torah prohibition of withholding a worker's wages overnight, from then on we assume that the employer remembers well whom he paid and whom he did not, since he would not have allowed himself to transgress a Torah prohibition. At that point the worker no longer swears and collects; rather, if the employer says that he paid, he is believed. He will still have to swear an oath of total denial, but there will be no room for the worker to collect.
The view of Rabbi Yehudah:
Rabbi Yehudah disagrees and holds that a hired worker does not swear and collect in every case, but only in a situation where there is a partial admission. How so? The worker claims fifty dinars as his wages, and the employer responds that he already gave him a gold dinar - worth twenty-five ordinary dinars. In other words, the employer admits that twenty-five dinars are still owed, and so he is admitting to part of the claim. Even so we do not believe him, since as explained he is preoccupied with his workers and may well not remember, and therefore we allow the worker to swear and collect on that basis.
Precisely in this case, where the employer admits to part of the claim - so that had he remembered, and had it been within his ability to remember, he would have been obligated to swear by Torah law - there the Sages instituted their enactment and ruled that the oath can be shifted to the other side, to the worker. But in a case where there is no partial admission, according to Rabbi Yehudah we would not do this.
In summary: In this Mishnah we learned the principle "kol hanishba'in sheba'Torah nishba'in velo meshalmin" - all those who swear by Torah law swear and do not pay, and in contrast to it the enactment of the Sages in the cases of "nishba'in venotlin" - they swear and collect: the hired worker, the victim of robbery, the injured party, one whose opponent is suspect regarding oaths, and the shopkeeper relying on his ledger. We examined the law of the hired worker - the reason for the enactment being the employer's preoccupation with his workers, the limitation of the law until the time payment comes due, and Rabbi Yehudah's approach, which restricts the enactment to a case of partial admission. The details of the remaining cases will be explained in the coming Mishnayos.