''He shall be impure'' (Numbers 19:13), indicating that the same halakhot apply in any case, unrelated to the manner in which he became impure.

The Gemara challenges: He requires that verse for a different derivation, as that which is taught in a baraita: The phrase ''He shall be impure'' serves to include one who immersed that day and whose purification process will be completed at nightfall. If he enters the Temple before nightfall, he is also liable to receive karet. The phrase later in that verse: ''His impurity is upon him,'' serves to include one who has not yet brought an atonement offering to complete the purification process, e.g., a leper or a zav. Rava said to Ravina: I said that the halakha that one rendered impure by a met mitzva is liable to receive karet is derived from the extraneous term ''yet,'' in the phrase later in that same verse: ''His impurity is yet upon him,'' which indicates that one is liable for entering the Temple in a state of impurity regardless of the manner in which he became impure. That is one version of the discussion.

Some teach this exchange with regard to this baraita: ''In plowing and in harvest you shall rest'' (Exodus 34:21). Rabbi Akiva says: This verse is referring to the Sabbatical Year. The Torah does not need to state the prohibition against plowing during the Sabbatical Year or harvesting during the Sabbatical Year, as it is already stated: ''You shall neither sow your field, nor prune your vineyard'' (Leviticus 25:4). What, then, is derived from this verse? Rather, it is derived that even plowing on the eve of the Sabbatical Year, which facilitates growth of crops when the Sabbatical Year enters, and the harvest of crops that grew during the Sabbatical Year, which emerged and were reaped after the conclusion of the Sabbatical Year, are prohibited.

Rabbi Yishmael says: This verse in Exodus is not referring to the Sabbatical Year; rather, the reference is to plowing and harvesting on Shabbat. Just as plowing is optional, as there is no case where there is a mitzva to plow per se, so too, the harvesting mentioned in the verse is optional. This serves to exclude from the prohibition the harvesting of barley for the omer offering, which is a mitzva, and is therefore permitted on Shabbat.

One of the Sages said to Rava: From where does Rabbi Yishmael ascertain that the plowing mentioned in the verse is referring to plowing that is optional? Perhaps the reference is to plowing a field to grow barley for use in the omer offering, which is a mitzva, and even so the Merciful One states: ''You shall rest.'' Rava said to him: Since if one found the field already plowed, he need not plow the field but he may directly proceed to sow the barley in the plowed field, clearly, even if one plows a field to facilitate fulfillment of a mitzva, plowing is not a mitzva per se.

Ravina raised an objection to the opinion of Rava from the clause of the mishna that states that the example of the forest serves to exclude a father who strikes his son, and a teacher who oppresses his student, and an agent of the court. And according to your opinion, why are a father who strikes his son and a teacher who oppresses his student excluded from exile? Let us say with regard to a father who strikes his son: Since if the son was learned, it is not a mitzva to strike him, now, in a case where the son is not learned and he strikes him to facilitate his education too, it is not a mitzva, and therefore he should be exiled. Rava replied: There, even if the son is learned, the father is performing a mitzva by striking him from time to time, as it is written: ''Chastise your son, and he will give you rest; and he will give delight to your soul'' (Proverbs 29:17).

Rava then said: That which I said is nothing, as there is a different proof that the verse is not referring to plowing that is a mitzva. Based on the juxtaposition of the two, it is derived that harvesting is similar to plowing: Just as in the case of plowing, if one found the field already plowed, he need not plow, as there is no case where there is a mitzva to plow per se, so too with regard to harvesting as well, as if one found the barley already harvested, he need not harvest. And if it enters your mind that the reference in the verse is to plowing and harvesting for the purpose of a mitzva, is it so that if one found the barley already harvested, he need not harvest? There is a mitzva to harvest and bring the barley for the omer offering. The prohibition in the verse applies only to harvesting that is optional.

MISHNA: The father is exiled to a city of refuge due to his unintentional murder of his son. And the son is exiled due to his unintentional murder of his father. Everyone is exiled due to their unintentional murder of a Jew, and a Jew is exiled due to his unintentional murder of any of them, except for the unintentional murder of a gentile who resides in Eretz Yisrael and observes the seven Noahide mitzvot [ger toshav]. And a ger toshav is exiled only due to his unintentional murder of a ger toshav.

GEMARA: The mishna teaches: The father is exiled to a city of refuge due to his unintentional murder of his son. The Gemara asks: But didn’t you say in the previous mishna: To exclude a father who strikes his son, who is not exiled? The Gemara answers: This mishna is referring to a son who is learned, and there is no mitzva to strike him; therefore, since the striking is optional, the father is exiled. The Gemara asks: But didn’t you say: Even if the son is learned, the father performs a mitzva by striking his son? The Gemara answers: This ruling of the mishna is stated with regard to a carpenter’s apprentice [bishevaleya]. Since the father is teaching his son carpentry, not Torah, there is no mitzva to strike him to spur him to study.

The Gemara challenges: In the case of a carpenter’s apprentice, his father is teaching him a livelihood, which is also a mitzva. The Gemara answers: The reference is to a son who has already learned another craft, and since he is able to earn his livelihood there is no mitzva to teach him a second craft.

§ The mishna teaches: And the son is exiled due to his unintentional murder of his father. And the Gemara raises a contradiction from a baraita. It is written: ''And a murderer shall flee there, one who strikes a person unintentionally'' (Numbers 35:11), from which it is derived that one who strikes a person is exiled. This serves to exclude one who strikes his father, whose punishment for doing so intentionally is more severe than that of the standard intentional murderer, and therefore the son is not subject to exile. Rav Kahana said: This is not difficult; this baraita is in accordance with the opinion of Rabbi Shimon, and that mishna is in accordance with the opinion of the Rabbis. Rabbi Shimon and the Rabbis disagree (Sanhedrin 50a) whether a son who kills his father intentionally is executed by strangulation or by the sword.

According to Rabbi Shimon, who says: Strangulation is more severe than execution by the sword, which is why a son who kills his father is liable to be executed by strangulation, one who commits the unwitting violation of a prohibition generally punishable by execution by the sword, i.e., intentional murder of one who is not a parent, is eligible for atonement by means of exile; one who commits the unwitting violation of a prohibition generally punishable by the more severe death of strangulation, i.e., intentional murder of a parent, is not eligible for atonement by means of exile.

By contrast, according to the Rabbis, who say: Execution by the sword is more severe than strangulation, which is why a son who kills his father is liable to be executed by the sword, a son who unintentionally kills his father has performed an unwitting violation of a prohibition generally punishable by execution by the sword. And one who commits an unwitting violation of a prohibition generally punishable by execution by the sword, i.e., intentional murder of one who is not a parent, is eligible for atonement by means of exile.

Rava says: That which was derived in the baraita that one who strikes a person is exiled, to exclude one who strikes his father, who is not exiled, is not referring to a son who unintentionally kills his father, as in that case the son is certainly exiled. Rather, it is to exclude one who inflicts a wound on his father unwittingly. The novel element of this derivation is that it enters your mind to say: Since in a case where he wounded his father intentionally, he is liable to be executed like a murderer (see Exodus 21:15), if he did so unwittingly, let him also be exiled like an unintentional murderer. Therefore, this derivation teaches us that exile is administered specifically to an unintentional murderer, but it is not administered to the unwitting performer of any other transgression.

§ The mishna teaches: Everyone is exiled due to their unintentional murder of a Jew, and a Jew is exiled due to his unintentional murder of any of them. The Gemara asks: Everyone is exiled due to their unintentional murder of a Jew: What case that was not already specified does this phrase serve to add? The Gemara answers: It serves to add a Canaanite slave and a Samaritan. The Gemara notes: We learn by inference from this mishna that which the Sages taught explicitly in a baraita: A Canaanite slave and a Samaritan are exiled and flogged due to a Jew, and a Jew is exiled and flogged due to a Samaritan and a Canaanite slave.

The Gemara analyzes the baraita: Granted, a slave and a Samaritan are exiled and flogged due to a Jew; either of them is exiled in a case where he killed a Jew unintentionally, and flogged in a case where he cursed the Jew, thereby violating a Torah prohibition. But with regard to the halakha that a Jew is exiled and flogged due to a Samaritan, granted, the Jew is exiled in a case where he killed the Samaritan unintentionally, but the Jew is flogged for violating what prohibition? For cursing the Samaritan? Isn’t that prohibition derived from the verse: ''And a leader in your people you may not curse'' (Exodus 22:27), from which it is inferred that the prohibition is in effect only with regard to one who performs an action characteristic of your people, who comports himself as an observant, God-fearing Jew? Even if the conversion of the Samaritans was valid, they regularly violate numerous prohibitions, and they do not comport themselves as observant Jews.

Rather, Rav Aḥa bar Ya’akov said: This baraita is not referring to lashes administered for cursing; rather, one is flogged in a case where a Jew testified against a Samaritan and a Samaritan testified against a Jew and he was rendered a conspiring witness. The Gemara asks: Does that mean that in the corresponding situation with regard to a Canaanite slave, a slave is flogged in a case where he testified against a Jew and was rendered a conspiring witness? Is a slave eligible to give testimony? Rather, Rav Aḥa, son of Rav Ika, said: What are we dealing with here? The Jew is flogged due to a slave and a Samaritan, and the slave and the Samaritan are flogged due to the Jew in a case where one struck the other with a blow