and Rabban Shimon Ben Gamliel holds that an effective challenge requires two witnesses, one could then ask: But doesn’t Rabbi Yoḥanan say: Everyone agrees that there is no effective challenge with fewer than two witnesses?

Rather, the challenge was established by two witnesses. And with what are we dealing here? We are dealing with a case where we presume with regard to the father of that man that he is a priest, and a rumor emerged about the son that he is the son of a priest and a divorced woman, or the son of a priest and a ḥalutza, and we downgraded him from the presumptive status of priesthood based on that rumor, and one witness came and said that the man in question is a priest of unflawed lineage, and we elevated him back to the priesthood, as one witness is sufficient to negate a rumor.

The Gemara continues the case: And then two witnesses came and said that he is the son of a divorced woman or the son of a ḥalutza, and we downgraded him from the priesthood based on their testimony. Then one witness came and said that he is a priest of unflawed lineage, resulting in two witnesses testifying that his lineage is unflawed, and two testifying that it is flawed. And everyone agrees that the testimony of the two single witnesses combine to produce testimony that he is a priest of unflawed lineage, and his presumptive status of priesthood should be restored.

The Gemara explains the dispute: And here it is with regard to concern about contempt of court that they disagree. Rabbi Elazar holds: Once we downgraded him from the presumptive status of priesthood based on the testimony of two witnesses, we do not then elevate him, as we are concerned about contempt of court, as a reversal in the court’s decision creates the impression that the court operates indecisively. And Rabban Shimon Ben Gamliel holds: We downgraded him from the presumptive status of priesthood and we then elevate him, and we are not concerned about contempt of court. The primary concern is that the matter should be determined based on the relevant testimonies.

Rav Ashi objects to the analysis that they disagree with regard to concern about contempt of court: If so, why specifically is it necessary to establish the dispute in a case where first one witness testified as to his unflawed lineage, and then another testified later? The same would hold true even in a case where two witnesses testified together that he is unfit for the priesthood and the court downgraded him, and two witnesses testified together that he is fit for the priesthood and the court elevated him. The tanna’im would also disagree, as the same concern applies. Rather, Rav Ashi said: Everyone agrees that we are not concerned about contempt of court. And here, it is with regard to whether the court is able to combine the testimony of two single witnesses that they disagree, and it is with regard to the issue that is the subject of the following dispute between these tanna’im.

As it is taught in a baraita (Tosefta, Sanhedrin 5:5): The testimony of individual witnesses never combines unless it is so that the two of them see the incident transpire together as one. Rabbi Yehoshua ben Korḥa says: Their testimony combines even in a case where they witnessed the event one after the other, but their testimony is established in court only if it is so that the two of them testify together as one. Rabbi Natan says: They are not required to testify together. Their testimony is combined even if the court hears the statement of this witness today and when the other witness arrives tomorrow the court hears his statement. Rabbi Elazar and Rabban Shimon ben Gamliel disagree in the dispute between Rabbi Natan and the Rabbis, whether the separate testimonies can be combined.

§ The Gemara relates an incident where two people disputed the ownership of land. There was a certain person who said to another: What do you want with this land of mine? The possessor said to him: I purchased it from you, and this is the bill of sale.