With regard to one who immersed but was not circumcised, everyone, i.e., both Rabbi Yehoshua and Rabbi Eliezer, agrees that the halakha is derived from the foremothers that immersion alone is effective. Where they disagree is with regard to one who was circumcised but had not immersed; Rabbi Eliezer derives that it is effective from the forefathers, and Rabbi Yehoshua disagrees because he maintains that in the conversion of the forefathers there was also an immersion.

The Gemara asks: From where did he derive this? If we say that he derived it from the fact that it is written that in preparation for the revelation at Sinai, God commanded Moses: “Go unto the people and sanctify them today and tomorrow, and let them wash their garments” (Exodus 19:10), as Rabbi Yehoshua understands that the washing mentioned in this verse is the ritual immersion of clothes, this leads to the following a fortiori inference: Just as in a case where one became impure through contact with some source of impurity, washing, i.e., immersion, of clothes is not required but immersion of one’s body is required, then in a case where washing of clothes is required, as in the preparation for the revelation at Sinai, isn’t it logical that immersion of one’s body should also be required?

The Gemara rejects the proof: But perhaps when the verse states that they had to wash their clothes, it was merely for cleanliness and not for the sake of ritual purity. If so, no a fortiori inference can be drawn from it to the case of immersion for ritual purity.

Rather, Rabbi Yehoshua derived it from here, where the verse states with regard to the formation of the covenant at Sinai: “And Moses took the blood and sprinkled it upon the people” (Exodus 24:8), and it is learned as a tradition that there is no ritual sprinkling without immersion. Therefore, our forefathers also must have immersed at Sinai, and consequently that is also an essential requirement for all conversions.

The Gemara asks: And with regard to the opinion of Rabbi Yehoshua, from where do we derive that also in the case of our foremothers there was immersion? The Gemara answers: It is based on logical reasoning, as, if so, that they did not immerse, then with what were they brought under the wings of the Divine Presence? Therefore, they also must have immersed.

Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: A man is never considered a convert until he is both circumcised and has immersed. The Gemara asks: Isn’t this obvious? In all disputes between an individual Sage and many Sages the halakha is in accordance with the opinion of the many Sages; it is therefore obvious that the halakha is in accordance with the Rabbis.

The Gemara explains: Who are the Rabbis referred to in the baraita? It is Rabbi Yosei. Since Rabbi Yosei is merely an individual Sage, it was necessarily for Rabbi Yoḥanan to state explicitly that the halakha is ruled in accordance with his opinion.

Rabbi Yosei’s opinion is as it is taught in a baraita: With regard to a convert who came and said: I was circumcised for the sake of conversion but I did not immerse, the court should immerse him, as what would be the problem with that; this is the statement of Rabbi Yehuda. Since in any case the court immerses him, Rabbi Yehuda does not require proof of the convert’s claim that he was circumcised for the sake of conversion because he holds that it is sufficient to be either circumcised or immersed for the sake of conversion. Rabbi Yosei says: The court does not immerse him. He holds that both circumcision and immersion must be performed specifically for the sake of conversion and are indispensable parts of the conversion process. Therefore, since it is impossible to verify the convert’s claim with regard to his circumcision, there is no benefit to having him immerse.

The baraita states a ramification of their dispute: Therefore, the court may immerse a convert who was already circumcised on Shabbat; this is the statement of Rabbi Yehuda. Since he holds that circumcision alone effected conversion, the immersion will not effect any further change in his status, and so it is permitted on Shabbat. And Rabbi Yosei says: The court may not immerse him. Since he holds that both circumcision and immersion are necessary to effect a conversion, the immersion will effect a change in his status by making him Jewish. Therefore it is prohibited to do so on Shabbat by rabbinic decree, because it appears similar to preparing a vessel for use.

The Gemara analyzes the latter clause: The Master said in the baraita: Therefore, the court may immerse a convert who was already circumcised on Shabbat. The Gemara asks: Isn’t this an obvious extension of his opinion; since Rabbi Yehuda said that either one of circumcision or immersion is sufficient, where a convert was circumcised in our presence the court may certainly immerse him, even on Shabbat. What, then, is the need for the baraita to include the clause that begins with: Therefore?

The Gemara explains: It is necessary to explicitly teach this ramification lest you say that according to Rabbi Yehuda the immersion is in fact the principal act that effects conversion, and when he said in the first clause that a convert who claims to have been circumcised should be immersed since there is no problem with that, his reasoning was that he holds it is only immersion that effects the conversion. And therefore performing the immersion on Shabbat would not be permitted, as it establishes the person with a new status and so would be prohibited by a rabbinic decree because it appears similar to preparing a vessel for use. The latter clause is therefore necessary to teach us that Rabbi Yehuda requires either this or that, i.e., either immersion or circumcision alone is sufficient to effect a conversion.

The Gemara analyzes the next statement in the baraita: Rabbi Yosei says: The court may not immerse him. The Gemara asks: Isn’t this an obvious extension of his opinion? As, since Rabbi Yosei requires two acts, both circumcision and immersion, to effect conversion, we may certainly not establish that person with a new status on Shabbat by completing his conversion by immersing him.

The Gemara explains: It is necessary to explicitly teach this ramification lest you say that according to Rabbi Yosei circumcision is in fact the principal act that effects conversion, and it is only there, in the first clause of the baraita, where the circumcision was not performed in our presence and so there is no way to verify whether it was done for the sake of conversion, that Rabbi Yosei states that the court should not proceed to immerse him; however, where the circumcision was performed in our presence, one might say that the conversion was already effected by the circumcision, and therefore let us immerse this convert on Shabbat. The latter clause is therefore necessary to teach us that Rabbi Yosei requires two acts, both circumcision and immersion, to effect conversion.

Rabba said: There was an incident in the house of Rabbi Ḥiyya bar Rabbi, and as Rav Yosef teaches it, Rabbi Oshaya bar Rabbi was also present, and as Rav Safra teaches it, a third Sage, Rabbi Oshaya, son of Rabbi Ḥiyya, was also present, in which a convert came before him who was circumcised but had not immersed. He said to the convert: Remain here with us until tomorrow, and then we will immerse you.

Rabba said: Learn from this incident three principles: Learn from it that a convert requires a court of three people to preside over the conversion, as Rav Safra taught that the case involved three Sages. And learn from it that one is not considered to be a convert until he has been both circumcised and immersed. And learn from it that the court may not immerse a convert at night, as they instructed him to remain there until the following day. The Gemara suggests: And let us say that one should also learn from it that we require a court of experts to preside over the conversion, as Rav Safra identified that three expert Sages were present. The Gemara rejects this: Perhaps they simply happened to be there, but in fact three laymen would suffice.

Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: A convert requires a court of three to preside over conversion, because “judgment,” is written with regard to him, as the verse states: “And one judgment shall be both for you and for the convert that sojourns with you” (Numbers 15:16), and legal judgments require a court of three judges.

The Sages taught in a baraita: With regard to someone who came and said: I am a convert, one might have thought that we should accept him; therefore, the verse states: “And if a convert sojourns with you in your land, you shall not oppress him” (Leviticus 19:33). The emphasis on “with you” suggests that only someone who was already presumed by you to be a valid convert should be accepted as a convert. If he came and brought witnesses to his conversion with him, from where is it derived that he is to be accepted? It is from the beginning of that verse, which states: “And if a convert sojourns with you in your land.”