It was due to his extraordinary wisdom, as it is written: “Say to wisdom: You are my sister” (Proverbs 7:4). Therefore, calling him: My sister’s son, was an indication of his great wisdom.

The Gemara had related that Rabbi Ḥiyya asked Rabbi Yehuda HaNasi: May Rav declare a firstborn animal permitted, and that Rabbi Yehuda HaNasi had responded: He may not declare such an animal permitted. The Gemara asks: What is the reason that he denied him this permission? If we say that it was because Rav was not sufficiently wise and learned, but that is difficult, as we already said that he was exceedingly wise. Rather, it must be that it was because, although he was quite knowledgeable about the halakha, he was not an expert with regard to blemishes, meaning that he lacked the practical expertise to apply the halakha to actual cases.

The Gemara rejects this answer. But didn’t Rav say: I apprenticed with a shepherd for eighteen months in order to be able to know which blemish is a permanent blemish, and which is a temporary blemish? Evidently, he had a high level of practical expertise in this matter. The Gemara explains: Rather, it was in order to bestow honor upon Rabba bar Ḥana. Rabbi Yehuda HaNasi wanted to ensure that Rabba bar Ḥana would be treated with respect, so he made sure that there was an area of halakha with regard to which the people would not be able to consult with Rav and would need to consult with Rabba bar Ḥana instead.

And if you wish, say instead: It is due to this fact itself: Since Rav was a great expert with regard to blemishes, he would permit blemishes that average people do not know about. And as a result, they would erroneously say with regard to a different blemish: In a case like this Rav declared the animal permitted, and in this way they would come to erroneously permit an animal with a temporary blemish, believing it to be identical to the blemish that Rav had declared permitted. Due to this concern, Rav was denied the authority to declare firstborn animals permitted on the basis of a blemish.

With regard to the permission granted to Rabba bar Ḥana and Rav, the Gemara had related that Rabbi Ḥiyya asked Rabbi Yehuda HaNasi: May he teach people and issue rulings concerning what is prohibited and what is permitted? And Rabbi Yehuda HaNasi responded: He may teach. The Gemara asks: If he had studied and mastered the relevant halakhot, why do I need him to receive permission? The need for formal authority is understandable when it comes to serving on a court to judge cases of monetary law, but any knowledgeable person should be qualified to answer questions about ritual law. The Gemara explains: The need for such permission is due to an incident that took place.

As it is taught in a baraita: Rabbi Yehuda HaNasi once went to a certain place, and he saw people there kneading dough while they were in a state of ritual impurity, and they believed that nevertheless, the dough remained ritually pure. Rabbi Yehuda HaNasi said to them: For what reason are you kneading your dough in a state of ritual impurity? They said to him: A certain Torah scholar came here and taught us that water from swamps [mei betza’im] does not render food susceptible to contract ritual impurity. Therefore, they would take water from swamps and knead dough with it, in the mistaken belief that such dough would not be susceptible to ritual impurity. But in reality, what he taught them was that water of eggs [mei beitzim], i.e., the albumin of eggs, does not render food susceptible to impurity, as it is not considered water. But they thought he said: Water from swamps.

And the residents of that same place erred also with regard to this: It was taught in a mishna (Para 8:10): The waters of the Keramiyyon River and the waters of the Piga River are not fit for mixing with ashes of the red heifer to use as water of purification, since they are water from swamps. And they erroneously thought: Since this water is not fit for use as water of purification, this means it is not considered water, and therefore it also does not render food susceptible to contracting impurity. But it is not so, as there, with regard to water of purification, we need: “Running water” (see Numbers 19:17), and water from swamps is not running water. But here, with regard to rendering food susceptible to impurity, any water renders food susceptible.

It was taught: At that time, when Rabbi Yehuda HaNasi discovered the consequences resulting from a Torah scholar who was not precise with his terminology, the Sages decreed: A Torah scholar may not teach halakha unless he receives permission from his teacher to do so. The teacher should not grant him this permission if he does not know how to express himself in a clear manner.

Concerning a similar matter, the Gemara relates: Tanḥum, son of Rabbi Ami, arrived at a place called Ḥatar, and he taught them: It is permitted to wash wheat in a small amount of water in order to make it easier to peel during the grinding process on Passover, and there is no concern that perhaps it will become leavened. They said to him: Isn’t Rabbi Mani from Tyre here i.e., near our location? And it is taught in a baraita: A Torah scholar may not teach halakha in the vicinity of his teacher, unless he is distant from the teacher by at least three parasangs [parsaot], corresponding to the size of the camp of Israel. In the encampment in the wilderness no one else judged cases, as all the Jewish people brought their cases to Moses (see Exodus 33:7). Tanḥum, son of Rabbi Ami, said to them: It did not enter my mind that Rabbi Mani was in the vicinity.

The Gemara relates: Rabbi Ḥiyya saw a certain man standing in a cemetery. He said to him: Are you not the son of so-and-so the priest? As it is prohibited for priests to come into contact with the dead (see Leviticus 21:1–4), Rabbi Ḥiyya was surprised to see a priest standing in a cemetery. The man said to him: Yes, but that man’s, meaning his own, father was a man with raised eyes who would desire things that he saw, even if they were forbidden. He set his eyes upon a divorcée and married her despite the Torah prohibition against such a union (see Leviticus 21:7), and thereby disqualified the offspring of that union from the sanctity of priesthood. As the son of a priest and a divorcée, the man had the status of a ḥalal and was therefore not obligated to abide by the restrictions specific to priests.

Continuing the discussion about receiving permission to teach halakha, the Gemara discusses the extent of this authority. It is obvious that one’s teacher can grant partial permission, meaning permission to rule on certain types of cases but not others, as it has been said above that doing so is effective. But what is the halakha with regard to granting such permission conditionally? Is it possible to grant permission limited to a certain period of time, or limited to a certain location? The Gemara suggests: Come and hear the solution to this matter from what Rabbi Yoḥanan said to Rav Shemen: You have our permission to instruct and to adjudicate until you return to us. This statement proves that it is possible to grant permission limited to a specific period of time.

§ Earlier, the Gemara discussed the possibility of a court consisting of only two judges adjudicating a case. Concerning the matter itself, Shmuel says: With regard to two judges who adjudicated a case, their judgment is a valid judgment, but they are called an impudent court. Rav Naḥman sat and said this halakha. Rava raised an objection to Rav Naḥman from a mishna (29a): In a case where three judges are adjudicating a case, even if two judges deem the defendant exempt from payment or two judges deem him liable to pay, and one says: I do not know, the judges must add another judge, since the one who abstained has removed himself from the court, and there are not enough judges. And if it is so as Shmuel says, they should be viewed as two judges who adjudicated the case, and there would be no need to add another judge, as a judgment passed by two judges is valid.

Rav Naḥman answered him: It is different there, as they convened from the outset with the knowledge that they are three and intended to judge the case with three judges. Therefore, if one abstains, they must add another to complete the quorum. But here they did not convene with the knowledge that they are three, but rather intended to adjudicate the case as a court of two judges.

Rava raised an objection to Rav Naḥman from a baraita: Rabban Shimon ben Gamliel says: Cases of monetary law are adjudicated by three judges, and mediation leading to compromise can be performed by two mediators. And the power of compromise is greater than the power of adjudication, as if two judges adjudicated a case, the litigants are able to withdraw from the case and demand a court with a complete quorum. But if two mediated a compromise, the litigants may not withdraw.