Makkot 3:1

(1) The LORD spoke to Moses, saying: (2) Speak to the Israelite people and say to them: I the LORD am your God. (3) You shall not copy the practices of the land of Egypt where you dwelt, or of the land of Canaan to which I am taking you; nor shall you follow their laws. (4) My rules alone shall you observe, and faithfully follow My laws: I the LORD am your God. (5) You shall keep My laws and My rules, by the pursuit of which man shall live: I am the LORD. (6) None of you shall come near anyone of his own flesh to uncover nakedness: I am the LORD. (7) Your father’s nakedness, that is, the nakedness of your mother, you shall not uncover; she is your mother—you shall not uncover her nakedness. (8) Do not uncover the nakedness of your father’s wife; it is the nakedness of your father. (9) The nakedness of your sister—your father’s daughter or your mother’s, whether born into the household or outside—do not uncover their nakedness. (10) The nakedness of your son’s daughter, or of your daughter’s daughter—do not uncover their nakedness; for their nakedness is yours. (11) The nakedness of your father’s wife’s daughter, who has born into your father’s household—she is your sister; do not uncover her nakedness. (12) Do not uncover the nakedness of your father’s sister; she is your father’s flesh. (13) Do not uncover the nakedness of your mother’s sister; for she is your mother’s flesh. (14) Do not uncover the nakedness of your father’s brother: do not approach his wife; she is your aunt. (15) Do not uncover the nakedness of your daughter-in-law: she is your son’s wife; you shall not uncover her nakedness. (16) Do not uncover the nakedness of your brother’s wife; it is the nakedness of your brother. (17) Do not uncover the nakedness of a woman and her daughter; nor shall you marry her son’s daughter or her daughter’s daughter and uncover her nakedness: they are kindred; it is depravity. (18) Do not marry a woman as a rival to her sister and uncover her nakedness in the other’s lifetime. (19) Do not come near a woman during her period of uncleanness to uncover her nakedness. (20) Do not have carnal relations with your neighbor’s wife and defile yourself with her. (21) Do not allow any of your offspring to be offered up to Molech, and do not profane the name of your God: I am the LORD. (22) Do not lie with a male as one lies with a woman; it is an abhorrence. (23) Do not have carnal relations with any beast and defile yourself thereby; and let no woman lend herself to a beast to mate with it; it is perversion. (24) Do not defile yourselves in any of those ways, for it is by such that the nations that I am casting out before you defiled themselves. (25) Thus the land became defiled; and I called it to account for its iniquity, and the land spewed out its inhabitants. (26) But you must keep My laws and My rules, and you must not do any of those abhorrent things, neither the citizen nor the stranger who resides among you; (27) for all those abhorrent things were done by the people who were in the land before you, and the land became defiled. (28) So let not the land spew you out for defiling it, as it spewed out the nation that came before you. (29) All who do any of those abhorrent things—such persons shall be cut off from their people.

Rabbi Yitzḥak says that like those liable to be executed, those liable to receive karet are not flogged. Those liable to receive karet for incest were included in the generalization: “For anyone who performs any of these abominations, the souls who do so shall be excised [venikhretu] from among their people” (Leviticus 18:29). Included in that category is one who engages in intercourse with his sister. And why then did the halakha of karet with regard to intercourse with one’s sister emerge from the generalization and receive specific mention: “And a man who takes his sister…and they shall be excised before the eyes of the children of their people” (Leviticus 20:17)? It is in order to sentence one who engages in intercourse with his sister with karet, and not with lashes. This is the source for the opinion that those liable to receive karet are not flogged.

(7) You shall sanctify yourselves and be holy, for I the LORD am your God. (8) You shall faithfully observe My laws: I the LORD make you holy. (9) If anyone insults his father or his mother, he shall be put to death; he has insulted his father and his mother—his bloodguilt is upon him. (10) If a man commits adultery with a married woman, committing adultery with another man’s wife, the adulterer and the adulteress shall be put to death. (11) If a man lies with his father’s wife, it is the nakedness of his father that he has uncovered; the two shall be put to death—their bloodguilt is upon them. (12) If a man lies with his daughter-in-law, both of them shall be put to death; they have committed incest—their bloodguilt is upon them. (13) If a man lies with a male as one lies with a woman, the two of them have done an abhorrent thing; they shall be put to death—their bloodguilt is upon them. (14) If a man marries a woman and her mother, it is depravity; both he and they shall be put to the fire, that there be no depravity among you. (15) If a man has carnal relations with a beast, he shall be put to death; and you shall kill the beast. (16) If a woman approaches any beast to mate with it, you shall kill the woman and the beast; they shall be put to death—their bloodguilt is upon them. (17) If a man marries his sister, the daughter of either his father or his mother, so that he sees her nakedness and she sees his nakedness, it is a disgrace; they shall be excommunicated in the sight of their kinsfolk. He has uncovered the nakedness of his sister, he shall bear his guilt.

The Gemara objects: One should also be flogged for violating a prohibition that entails fulfillment of a positive mitzva where the Torah provides the means to rectify the transgression through performance of a positive mitzva, as it does involve an action.

(Or differently translated: A prohibiton removed to the remedy of a positive commandment, should also be subject to makkot, since it too is included in the statement: if you will not be vigilant to perform all of the commands and it is violated through action.)

Yet the halakha is that one is not flogged for violating that type of prohibition.

The Gemara rejects that contention: One is not flogged in that case because lashes are administered only for violation of prohibitions similar to the prohibition of muzzling an ox while it is threshing grain (see Deuteronomy 25:4). The Torah juxtaposed that prohibition to the halakhot of lashes in the same passage, from which it is derived that lashes are administered only for violations similar to muzzling, i.e., a prohibition that does not entail fulfillment of a positive mitzva.

Rabbi Abbahu says: The Torah explicitly included with regard to lashes those liable to receive karet, as is derived by means of a verbal analogy: “And they shall be excised [venikhretu] before the eyes of [le’einei] the children of their people” (Leviticus 20:17), from: “Forty he shall flog him…and your brother shall be dishonored before your eyes [le’einekha]” (Deuteronomy 25:3). Rabbi Abba bar Memel objects to this: If so, the inclusion of those liable to be executed with court-imposed death penalties should also be learned by means of a verbal analogy: “If from the eyes of [me’einei] the assembly it was performed unwittingly” (Numbers 15:24) stated with regard to idol worship, for which one is liable to be executed, from: “Before your eyes,” stated with regard to lashes. On that basis, one should derive that those liable to be executed with a court-imposed death penalty should also be flogged.

(17) If a man marries his sister, the daughter of either his father or his mother, so that he sees her nakedness and she sees his nakedness, it is a disgrace; they shall be excommunicated in the sight of their kinsfolk. He has uncovered the nakedness of his sister, he shall bear his guilt.

(3) He may be given up to forty lashes, but not more, lest being flogged further, to excess, your brother be degraded before your eyes.