The Gemara asks: And let us see from whom he took the money, as it will be obvious that he is the one who bought it. The Gemara answers: No, it is necessary to teach this halakha in a case where the seller took money from both of them, and he then said: One payment I accepted willingly, and one payment was given to me against my will, and it is not known which person gave him money in accordance with his will and which did so against his will. In that case, if the item is no longer in the seller’s possession, he is not deemed credible to testify to whom he sold it.

The Gemara cites the continuation of the baraita: Similarly, a judge is deemed credible to say: I found this person victorious in a civil case, and I found this one obligated to pay. In what case is this statement said? When the litigants are still standing before him. But if the litigants are not standing before him but have left, he is not deemed credible. The Gemara asks: And let us see who holds the writ of a favorable verdict. Why is there a need to rely on the statement of the judge?

The Gemara answers: No, it is necessary to teach this halakha in a case where their writs of a favorable verdict have been torn up and cannot be examined. The Gemara asks: If so, then let him return and judge them again, and presumably the same verdict will be issued. The Gemara answers: It was a case of the judges’ discretion [shuda dedayyanei]. In certain cases, the verdict depends on the decision of the judges based solely on their sense of which litigant deserves to win. There is no guarantee that they will make the same decision the second time around.

The Gemara continues to discuss the credibility of various people with regard to a firstborn. Rav Naḥman says: Three are deemed credible with regard to stating that a child is a firstborn, and they are: A midwife, his father, and his mother. A midwife is deemed credible only immediately; his mother is deemed credible all of the first seven days after his birth; his father is deemed credible forever. As it is taught in a baraita: Expounding the verse: “But he shall acknowledge the firstborn” (Deuteronomy 21:17), the Sages said: The father shall acknowledge him to others. In other words, he is deemed credible to tell others that this is his firstborn.

From here, Rabbi Yehuda said: A person is deemed credible to say: This is my firstborn son. And just as he is deemed credible to say: This is my firstborn son, so too, if he is a priest he is deemed credible to say about his son: This is a son of a divorced woman, or: This is a son of a ḥalutza. And the Rabbis say: As far as these latter claims are concerned, he is not deemed credible. He is deemed credible to state only which son is his firstborn.

§ The mishna teaches that Abba Shaul would call a shetuki by the label of beduki. The Gemara asks: What is the meaning of beduki? If we say that they examine [bodekin] his mother, and if she says: I engaged in sexual intercourse with a man of unflawed lineage, in which case she is deemed credible, then with whose opinion does this halakha accord? With that of Rabban Gamliel. But we already learned this on another occasion, as we learned in a mishna (Ketubot 13a): If an unmarried woman was pregnant, and they said to her: What is the status of this fetus, and she said to them: It is from so-and-so, and he is a priest, then Rabban Gamliel and Rabbi Eliezer say: She is deemed credible, and Rabbi Yehoshua says: We don’t live from, i.e., we don’t rely on, the words of her mouth, and she is not trusted. And Rav Yehuda says that Shmuel says: The halakha is in accordance with the opinion of Rabban Gamliel. What, then, did Abba Shaul add beyond what was taught in that mishna?

The Gemara answers: Abba Shaul’s statement that the woman is deemed credible when she states that the father of the child was of unflawed lineage is nevertheless necessary. One halakha was stated in order to render her fit to marry a priest, and one halakha was stated to render her daughter fit to marry a priest as well. The Gemara asks: This works out well according to the one who says: According to the statement of the one who deems her fit to marry a priest, he nevertheless deems her daughter unfit, as her credibility does not extend to her daughter, who never had a presumptive status of unflawed lineage. Abba Shaul therefore presents a novel ruling, that if she claims to have engaged in intercourse with a man of unflawed lineage, she is deemed credible even with regard to the status of her daughter.

But according to the one who says: According to the statement of the one who deems her fit to marry a priest, he deems her daughter fit to do so as well, what is Abba Shaul coming to teach us?

The Gemara answers: The statement of Abba Shaul is preferable and is more far-reaching than that of Rabban Gamliel, as, if the halakha were learned only from there, the case of an unmarried woman, I would say: There it is a case when most are fit with regard to her, as it is permitted for most people to engage in intercourse with a single woman. But in a circumstance where most are unfit with regard to her, e.g., if she was betrothed and claimed that the man betrothed to her was the father, you might say this: She is not deemed credible when she claims to have engaged in intercourse with a man that would result in the child being of unflawed lineage, as only a small minority of people, i.e., her betrothed, would not render the child unfit, while the rest of the people in the world would render him unfit. Therefore, Abba Shaul’s halakha was necessary in order to include that case. Rava says: The halakha is in accordance with the statement of Abba Shaul.

MISHNA: All those for whom it is prohibited to enter into the congregation, i.e., to marry a Jew of unflawed lineage, are permitted to marry into each other’s families. Rabbi Yehuda prohibits them from marrying anyone other than those who share their specific flaw.

Rabbi Eliezer says: It is permitted for those with definite flaws to marry with those with definite flaws. For example, it is permitted for mamzerim and Gibeonites to marry each other. By contrast, it is prohibited for those with definite flaws, such as mamzerim, to marry with those whose flaws result from an uncertainty, such as a child of unknown paternity [shetuki] and a foundling; and it is prohibited for those whose flaws result from an uncertainty to marry with those with definite flaws; and it is prohibited for those whose flaws result from an uncertainty to marry with those whose flaws result from an uncertainty, such as a shetuki and a female shetuki. And these are the ones whose flaws result from an uncertainty: A shetuki, a foundling, and a Samaritan.

GEMARA: What is the meaning of: All those for whom it is prohibited to enter into the congregation? If we say mamzerim and Gibeonites, shetukim, and foundlings, wasn’t it already taught in the first clause of the first mishna of the chapter that with regard to mamzerim and Gibeonites, shetukim, and foundlings, it is permitted for men and women in these categories to marry into each other’s families?

And furthermore, to which case in the mishna here is it referring when it states: Rabbi Yehuda prohibits them? If we say it is referring to those with definite flaws marrying with those whose flaws result from an uncertainty, and it is teaching that Rabbi Yehuda prohibits them from marrying each other, this is difficult. But from the fact that it teaches in the latter clause that Rabbi Eliezer says: It is permitted for those with definite flaws to marry with those with definite flaws; by contrast, it is prohibited for those with definite flaws to marry with those whose flaws result from an uncertainty, and it is prohibited for those whose flaws result from an uncertainty to marry with those with definite flaws, and it is prohibited for those whose flaws result from an uncertainty to marry with those whose flaws result from an uncertainty; then by inference, it is clear that Rabbi Yehuda does not maintain this opinion.

And if you would say that when Rabbi Yehuda prohibits those with flawed lineage from marrying each other, he is referring to the prohibition against a convert marrying with a mamzeret, does the mishna teach the halakha of a convert marrying with a mamzeret? It teaches: All those for whom it is prohibited to enter into the congregation, which does not include a convert.

Rav Yehuda says: