The 336th prohibition is that one is forbidden from having relations with one's daughter.
This mitzvah is not explicitly stated in the Torah; it does not say, "do not commit incest with your daughter," for example. The Torah already prohibited relations with one's son's daughter and one's daughter's daughter, although they are more remotely related. It is therefore obvious [that a daughter is prohibited] and it is not mentioned.
In tractate Yevamos it is said, "the actual prohibition of [incest with] a daughter is learned by means of derivation,1 as Rava said, 'Rabbi Yitzchok bar Avdimi said to me: "compare the two occurrences of the word heinah [they are] and the two occurrences of the word zimah [perversion].' "
The explanation of this passage: regarding the incestual prohibition of one's son's daughter and one's daughter's daughter, the verse says,2 "for they are [heina] your own nakedness." Regarding the prohibition [of marrying] a woman and her daughter, son's daughter, or daughter's daughter, the verse says,3 "since they are [heinah] relatives, it is perversion."
[Since both verses have the word heinah, we can use the principle of gezeirah shavah,4 and compare the two verses:] just as where there is a prohibition [against marrying] a woman together with her son's daughter or daughter's daughter, the same applies to her daughter5 — so too where there is a prohibition [from having relations with] one's son's daughter or daughter's daughter, the same applies to one's daughter.6
Regarding the appropriate punishment, the verse states,7 "if a man marries a woman and her mother, it is perversion [zimah], and both he and they8 shall be burned with fire." So too, the punishment [for marrying] a woman and her daughter's daughter or son's daughter is burning, since regarding them the verse9 says zimah,10 just as it does by a woman and her daughter.11
Tractate Kerisus12 says, "do not treat a gezeirah shavah lightly, because [the prohibition of incest with] a daughter is part of the main body of the Torah,13 and nevertheless the verse does not teach it to us [explicitly] except through a gezeirah shavah14 — 'compare the two occurrences of the word heinah and the two occurrences of the word zimah.' "
Think closely into the wording of the Sages, "the verse does not teach it to us," rather than, "we have not learned it." They said it in this way because all teachings of this category have been handed down to us through "The Emissary,"15 and they are part of Torah tradition, as we explained in the introduction to our explanation of the Mishneh.
The verse does not mention this prohibition explicitly because it can be derived from a gezeirah shavah. This is their intention in saying, "the verse does not teach it to us [explicitly] except through a gezeirah shavah." And their statement, "main body of the Torah" is sufficient [to teach us that this mitzvah counts as one of the 613].
The conclusion of this discussion is that one who transgresses the prohibition of [incest with] one's daughter, daughter's daughter, or son's daughter is punished by s'reifah.16 If the act was intentional, but no one knows of the transgression, or there was no valid testimony, the punishment is kares.17 If one of them transgressed unintentionally, that person must bring a sin-offering.18
