Kommentar zu Wajikra 18:15

אשת בנך [THE NAKEDNESS OF THY DAUGHTER-IN-LAW THOU SHALT NOT UNCOVER; SHE IS] THY SON'S WIFE — By using the apparently redundant words: “she is thy son's wife" Scripture says, as it were: I command this about such a woman only when thy son has a legal matrimonial relation (אישות) to her, thus excluding a woman who has been raped by him (אנוסה) or a Canaanitish maid-servant, or a non-Jewess (cf. Sifra, Kedoshim, Chapter 10 10)).

Excluding a woman raped. Rashi does not say “[excluding] a woman raped” above (verse 11) regarding “the nakedness of the daughter of your father’s wife,” because above we include [the daughter of] a raped woman to make one liable, since it is written (verse 9), “your father’s daughter,” and Rashi explains, “Even the daughter of a [woman] raped [by your father].” You might ask: What is the difference that here, the verse “your son’s wife” excludes even “a woman raped,” whereas regarding “the nakedness of your father’s wife” we do not exclude a woman raped? If this is because the verse above includes her by writing “your father’s daughter,” which implies even the daughter of a raped woman, here too it is written “your daughter-in-law,” which should imply even a raped woman? Re’m answers: “There it is different, as there are two verses and each one is expounded separately. And since one (verse 9) implies even a raped woman and one (verse 11) implies that we exclude a raped woman, in order to prevent a contradiction they expounded that it [verse 11] only comes to exclude a handmaiden or a non-Jewish woman in order to resolve [the apparent contradiction between] both verses. But here where the inclusion and the exclusion are in the same verse, they are not expounded separately. Rather each one explains the other. What daughter-in-law did I prohibit? The one that your son has a marital relationship; however, a raped woman etc., with whom your son does not have a marital relationship...