We'll now talk about the fourth person who would swear and collect. In other words, we have the person bringing the claim swear, and we allow him to collect based on his oath. We said this applies when the person he is dealing with would not be trusted to take an oath. If a person brings a claim against somebody, the person he is bringing the claim against would usually take an oath and would not have to pay. But if we don't trust him to swear, for whatever reason, as we'll discuss in the Mishnah, then we transfer the oath and allow the person bringing the claim to swear and collect. The Mishnah here lists all the different aveirot (transgressions) a person could commit that would make him untrustworthy.
What are the situations in which the person being sued, for example, is not trusted to take an oath? He may have sworn falsely in an oath of testimony, or about a deposit he was holding, or in a regular shevuat shav: if he used the name of God, he swore falsely. We say that he violated an issur (prohibition), and therefore we no longer trust him to swear. We also do not trust a thief to swear in court. We'll list different people who, even though they aren't actually thieves, we disqualify at the deRabbanan (rabbinic level) and don't trust because they deal unethically with money. One of them was a person who played with dice—he gambled for money. That person lacks fear of Hashem. He lives an empty lifestyle; he doesn't benefit the world whatsoever. He's not working, studying Torah, or doing acts of kindness; his mind is always on gambling. This includes somebody who lends money on interest, which is prohibited by the Torah. If people are involved in money illegally, they're considered thieves. Also included is somebody who races pigeons for money; that's another type of gambling. Somebody who does business with Shemitah produce, which you're not allowed to do business with; it's only for eating. They're so willing to violate the Torah in order to make money that we never know what they're willing to do, including perhaps swearing falsely for money.
So in all of these cases, the person being brought a claim against is not trusted to swear. Once the person bringing the claim swears, he collects, instead of having the person being claimed against swear. What if both people involved were suspected of doing certain things and were both not allowed to swear? The person bringing the claim and the person the claim is against both can't swear. The oath goes back to its original place: the original person obligated to take it, the defendant. Since he's unable to swear, we say he has to pay. We don't trust him to swear in order to hold on to his money against the claim being made against him. Therefore, he has to pay up, because he can't protect himself by swearing. That's the opinion of Rebbe Yosei. Rebbe Meir says that since neither one of them has the ability to swear right now, we say to divide the money they're fighting over. The defendant pays out half of the claim against him.