Apparently, both Reish Lakish and Rav Yeimar bar Rabbi Shelemya hold that it is prohibited to issue a warning. Both are of the opinion that the word kinnui is a term for anger. Since causing anger is a negative trait, it follows that it is prohibited to issue a warning.

The Gemara asks: And according to the one who says that it is permitted for him to issue a warning, what is the meaning of the term kinnui? Rav Naḥman bar Yitzḥak says: The term kinnui means nothing other than a term of forewarning, and so it says: “Then the Lord warned [vayekanneh] concerning His land and had pity for His people” (Joel 2:18). As detailed in that passage, the Lord ordered the locusts to stop destroying Eretz Yisrael.

It is taught in a baraita that Rabbi Meir would say: A person commits a transgression in private and the Holy One, Blessed be He, proclaims about him openly, i.e., in public, that he transgressed, as it is stated concerning a sota, who transgressed in private: “The spirit of jealousy came [avar] upon him” (Numbers 5:14); and the term avira means nothing other than a term of proclamation, as it is stated: “And Moses gave the commandment, and they caused it to be proclaimed [vaya’aviru] throughout the camp” (Exodus 36:6).

Reish Lakish says: A man commits a transgression only if a spirit of folly [shetut] enters him, as it is stated: “If any man’s wife goes aside [tisteh]” (Numbers 5:12). The word tisteh is written with the Hebrew letter shin, affording an alternative reading of tishteh, which is related to the term for folly, the word shetut.

§ The Gemara discusses why the testimony of one witness suffices with regard to defilement. The school of Rabbi Yishmael taught a baraita: For what reason did the Torah deem credible a single witness with regard to the defilement of a sota? It is because there is a basis for anticipating the matter, as there is strong circumstantial evidence that she committed adultery. What is the basis for anticipating the matter? As he warned her not to seclude herself with a specific man, and she nevertheless secluded herself with him, and one witness testifies that she is defiled, then the combination of her behavior and the testimony renders it reasonable to assume that she has in fact committed adultery.

Rav Pappa said to Abaye: But when the warning is written in the Torah, it is written in the verse after seclusion and defilement are mentioned, indicating that the circumstance in which one witness is deemed credible with regard to defilement is even when there was no previous warning. The order in which the Torah describes the sota process seems to indicate that the husband’s warning is issued only after the wife already secluded herself with the other man and was defiled, as the verses state: “And a man lie with her carnally, and it was hidden from the eyes of her husband, and she was defiled secretly, and there is no witness against her, and she was not taken. And the spirit of jealousy came [ve’avar] upon him, and he warned his wife, and she had become defiled” (Numbers 5:13–14).

Abaye said to him in response: That which the verse states: “And the spirit of jealousy came [ve’avar] upon him,” means: And it had already come upon him, that the husband warned his wife not to seclude herself with a specific man prior to her seclusion and defilement.

The Gemara asks: If that is so, that “ve’avar” is referring to a matter that already occurred, then in the case of the agreement between Moses and the tribes of Gad and Reuben before they entered Eretz Yisrael, where he stated: “And every armed man of you will pass over [ve’avar] the Jordan” (Numbers 32:21), so too did he mean that they had already crossed? Moses was stipulating a condition with regard to the future; they had yet to cross the Jordan.

The Gemara answers: There, from the fact that it is written: “And the land be subdued before the Lord, and you return afterward” (Numbers 32:22), it is clear that it teaches concerning the future. But here, if it enters your mind that the verses should be understood as they are written in the Torah, that “ve’avar” (Numbers 5:14) is after the defilement and seclusion, then why do I need a warning? If the woman had already secluded herself with the man and become defiled, the husband’s warning would be irrelevant, as she had already become forbidden to him. Therefore, the word ve’avar in this context must be referring to a past event, i.e., the husband issuing a warning to his wife prior to the seclusion.

The school of Rabbi Yishmael taught: A man issues a warning to his wife only if a spirit entered him, as it is stated: “And the spirit of jealousy came upon him, and he warned his wife” (Numbers 5:14). The Gemara asks: Of what spirit does Rabbi Yishmael speak?

The Rabbis say: A spirit of impurity, as one should not issue a warning to one’s wife. Rav Ashi says: A spirit of purity, as issuing a warning indicates that he will not tolerate promiscuous behavior.

The Gemara comments: And it stands to reason like the one who says that Rabbi Yishmael was speaking of a spirit of purity, as it is taught in a baraita: “And he warned his wife,” i.e., the issuing of the warning, is optional, that the husband is neither enjoined to nor prohibited from issuing a warning; this is the statement of Rabbi Yishmael. Rabbi Akiva says: It is mandatory, as one who sees his wife behaving in an inappropriate manner with another man is obligated to warn her. The Gemara explains: Granted, if you say that Rabbi Yishmael was speaking of a spirit of purity, then it is well, as it may be optional, or even mandatory, to issue a warning. But if you say that he was speaking of a spirit of impurity, can it be optional or mandatory for a person to introduce a spirit of impurity into himself? The Torah would not require a husband to act in a manner that results from having a spirit of impurity enter him.

§ The Gemara discusses the matter itself. “And he warned his wife,” i.e., the warning, is optional; this is the statement of Rabbi Yishmael. And Rabbi Akiva says: It is mandatory. The Gemara notes that Rabbi Yishmael and Rabbi Akiva engage in a similar dispute with regard to several other verses. Although under normal circumstances it is prohibited for a priest to become ritually impure through contact with a corpse, the verse states that he may do so for the sake of burying his relatives. The baraita teaches: “For her may he become impure” (Leviticus 21:3), i.e., for a priest to participate in the burial of his sister, despite the fact that he will contract ritual impurity, is optional; this is the statement of Rabbi Yishmael. A priest is not obligated to participate, but he may. And Rabbi Akiva says: It is mandatory for him to do so.

The verse states: “Of them may you take your bondmen forever” (Leviticus 25:46), i.e., keeping one’s Canaanite slave forever, is optional, this is the statement of Rabbi Yishmael. One is not enjoined against emancipating a Canaanite slave, but one is permitted to keep his Canaanite slaves forever. Rabbi Akiva says: It is mandatory, and it is prohibited for one to free his Canaanite slave.

Rav Pappa said to Abaye, and some say that Rav Mesharshiyya said to Rava: Shall we say that Rabbi Yishmael and Rabbi Akiva disagree in this manner with regard to the entire Torah? In other words, is it so that whenever there is a statement where it is unclear whether it is referring to an optional or mandatory act, that one master, Rabbi Yishmael, says that it is optional, and the other master, Rabbi Akiva, says that it is mandatory. Abaye said to Rav Pappa in response: Here, in these particular cases, they disagree with regard to the meaning of these specific verses, but it is not a general dispute.

The Gemara explains their dispute in these specific contexts, beginning with the dispute concerning a man’s warning to his wife: “And he warned his wife,” the warning is optional; this is the statement of Rabbi Yishmael. Rabbi Akiva says: It is mandatory.

What is the reason of Rabbi Yishmael? He holds in accordance with the statement of this tanna, as it is taught in a baraita: Rabbi Eliezer ben Ya’akov says: With regard to that which the Torah said: “You shall not hate your brother in your heart” (Leviticus 19:17), one might have thought that this prohibition applies in a case such as this one, when one sees his wife behaving improperly with another man, and the verse would instruct the husband to avoid conflict and strife. Therefore, the verse states: “And the spirit of jealousy came upon him, and he warned his wife” (Numbers 5:14), teaching that it is permitted for one to issue a warning to his wife in such a case.

The Gemara asks: And how does Rabbi Akiva derive that it is mandatory? The Gemara answers: There is another warning written in the same verse, as the entire verse reads: “And the spirit of jealousy came upon him, and he warned his wife, and she be defiled; or if the spirit of jealousy came upon him, and he warned his wife, and she be not defiled.” Therefore, the first half of the verse teaches that it is permitted to issue a warning, and the second half teaches that it is in fact mandatory.

The Gemara asks: And how does Rabbi Yishmael explain the repetition? The Gemara answers: Since it needed to write in this verse both possibilities as to whether the woman was unfaithful: “And she be defiled,” and also: “And she be not defiled,” to teach that although it is uncertain whether she had become defiled, she is still forbidden to her husband, therefore, it is also written: “And he warned his wife,” a second time. This repetition should not be interpreted as rendering the issuance of the warning as mandatory.

This manner of interpreting verses is as taught by the school of Rabbi Yishmael, as the school of Rabbi Yishmael taught: Every passage in the Torah that was stated and repeated was repeated only for the novel element introduced therein. Although the Torah could have merely mentioned the element necessary to teach an additional halakha, one should not interpret the repetition of a previously mentioned matter as teaching a second additional halakha, as the style of the Torah is to repeat a passage even to teach only one additional halakha. In the case of the passage concerning a sota as well, the repetition of the warning does not teach a new halakha.

The Gemara discusses the second dispute between Rabbi Yishmael and Rabbi Akiva. The baraita teaches: “And for his sister a virgin, that is near to him, that has had no husband, for her may he become impure” (Leviticus 21:3), i.e., for a priest to participate in the burial of his sister despite the fact that he will contract ritual impurity is optional; this is the statement of Rabbi Yishmael. A priest is not obligated to participate, but he may do so. Rabbi Akiva says: It is mandatory for him to do so.

What is the reason of Rabbi Yishmael? Since it is written: “Speak to the priests, the sons of Aaron, and say to them: There shall none become impure for the dead among his people” (Leviticus 21:1), indicating that a priest is enjoined from contact with the dead, it was necessary to be written: “For her may he become impure,” which teaches that a priest may become impure at the burial of a relative.

The Gemara asks: And how does Rabbi Akiva derive that it is mandatory? The Gemara answers: He derives that it is permissible from the previous verse, which states: “Except for his kin, that is near to him” (Leviticus 21:2). Since it is derived that it is permitted from that verse, why do I need the additional verse: “For her may he become impure”? To teach that it is mandatory.

The Gemara asks: And how does Rabbi Yishmael explain the repetition? The Gemara answers: He explains that the verse teaches that he may become impure for her, but he may not become impure to bury only one of her limbs. This additional verse teaches that a priest may become ritually impure to bury a relative only in the case of burying a complete body.