where an oath cannot be imposed by one witness, as two witnesses must testify that the wife secluded herself with the man concerning whom she was warned in order for her to be obligated to take the oath of a sota, and yet one can extend her oath, is it not logical that with regard to a claim involving money, where an oath can be imposed by the testimony of one witness, that one can extend the oath?

The Gemara asks: We found a source for the extension of an oath in the case of a definite claim, i.e., when the plaintiff is certain of his claim. From where do we derive that this halakha of the extension of an oath applies also to uncertain claims, when the plaintiff is not sure the defendant owes him money but merely suspects this to be the case?

The Gemara answers: It is taught in a baraita that Rabbi Shimon ben Yoḥai says: The Torah states an external oath, i.e., an oath administered outside of the Temple, and it states an internal oath, an oath administered inside the Temple courtyard, i.e., the oath of a sota. Just as with regard to an oath stated in the Torah that is taken inside the Temple, the Torah rendered uncertainty like certainty, as in the case of a sota the husband’s claim is based on suspicion and yet he can extend that oath; so too, with regard to an oath stated in the Torah that is taken outside the Temple, the Torah rendered uncertainty to be like certainty, i.e., all oaths can be extended to include even uncertain claims.

§ The Gemara asks: Until where does the extension of an oath reach? It has been established that a plaintiff can attach other claims to the oath that the defendant is required to take, even if they do not relate to the current claim submitted in court. To what extent can the plaintiff impose additional oaths? Rav Yehuda said that Rav said: The halakha is that a plaintiff can even say to a defendant: Take an oath to me that you are not my Canaanite slave. If the defendant is required to take an oath, e.g., concerning denial of a debt, he can be forced to take an oath about this matter as well.

The Gemara asks: But the court ostracizes one who says this to another, as it is taught in a baraita: One who calls another a slave shall be ostracized. One who calls another a mamzer incurs the punishment of forty lashes. If one calls another a wicked person then the insulted person may harass him in all aspects of his life. In light of this halakha, it is clear that the court will not force the accused to respond to this insult by taking an oath.

Rather, Rava said that the plaintiff can extend an oath by stating: Take an oath to me that you were not sold to me as a Hebrew slave. In this case the plaintiff is not questioning the man’s lineage, as he is simply claiming that he was sold to him as a slave and must work for him. The Gemara asks: But there is nothing novel about this halakha, as this is a proper claim that there is money owed to him by the accused. The sale and service of a Hebrew slave can be assessed in monetary terms, and is analogous to all claims of debt, which can be imposed by extension of an oath. The Gemara answers: Rava conforms to his line of reasoning, as Rava says: The Hebrew slave himself is acquired by his master. Consequently, this claim involves not just money but ownership over his person as well.

The Gemara asks: If so, this is similar to a claim concerning ownership of land, and the mishna already taught that an oath can be extended to include a claim concerning land. The Gemara answers: This ruling is necessary lest you say: It is land that people are likely to sell privately, and if it is so that the plaintiff had sold it to him, the sale would not have generated publicity, and the public would not know about it. Therefore, the plaintiff’s claim that the defendant sold land to him is reasonable.

By contrast, in this case, where the plaintiff claims that he purchased the defendant as a Hebrew slave, if it is so that he purchased him as a slave, the sale would have generated publicity. Since this supposed sale is not common knowledge, one might have thought that the defendant cannot be forced to take an oath to deny this claim. Therefore, Rava teaches us that despite the absence of public knowledge, one can extend an oath to this claim as well.

MISHNA: The mishna discusses a transaction involving the barter of two items. With regard to all items used as monetary value for another item, i.e., instead of a buyer paying money to the seller, they exchange items of value with each other, once one party in the transaction acquires the item he is receiving, this party is obligated with regard to the item being exchanged for it. Therefore, if it is destroyed or lost, he incurs the loss. How so? If one exchanges an ox for a cow, or a donkey for an ox, once this party acquires the animal that he is receiving, this party is obligated with regard to the item being exchanged for it.

GEMARA: The Gemara asks: What is the item given in exchange mentioned in the mishna? If it is referring to a coin, for which property is usually exchanged, can one learn from the mishna that a coin can effect exchange, i.e., it is possible to perform the act of acquisition of exchange, either a standard exchange or a symbolic exchange, using coins? This is problematic, as the halakha is that coins cannot be used for this act of acquisition. Rav Yehuda said: The phrase: All items used as monetary value for another item, is not referring to a coin. Rather, this is what the mishna is saying: With regard to all items that can be appraised when used as monetary value for another item, i.e., that their value can be appraised relative to the value of another item, excluding a coin, whose value is apparent,