(a) The Gemara presents a scenario - involving Eshes Achiv she'Lo Hayah b'Olamo - where two brothers can be Meyabem two sisters according to Rebbi Shimon. The case involves 8 of Yakov's children, from Reuven to Zevulun, skipping Dan and Naftali. Why did it skip them and jump to Gad and Asher?
(b) Also, on Daf 9b, when Rashi describes a case where two brothers can be Meyabem two sisters who are each Eshes Achiv me'Imo to one brother, he brings in Reuven, Shimon, Levi, Yehudah, Yisachar, and Naftali . Wouldn't he have done better to mention Zevulun instead of Naftali (like the Gemara does here)? And if he mentioned Naftali because the mother of the child (in the case Rashi presents) is named Bilhah - then why did he choose to name the son of Zilpah (in the case Rashi presents) as Yisachar, and not Gad or Asher like the Gemara here?
Lawrence Foux, London, England
Your points are excellent, Bobby. Every word of the Gemara and Rashi is written with care, and if we pay attention to even the smallest of details, we will certainly grow from it.
(a) The key here is that the names that the Gemara used were chosen to help us remember the cases more easily.
The Gemara's example uses the sons of Leah since we are looking for an easily recognized sixsome of brothers. Gad and Asher are more closely associated (in the mind) with Leah's children than Dan and Naftali because they were the sons of Zilpah, Leah's maidservant. In fact, the Torah itself lists the sons (and grandsons) of Zilpah along with those of Leah (Bereishis 46:16), rather than putting them after the sons of Bilhah.
(b) Your second question is a much stickier one, and I do not have a complete answer for you.
I suppose we could propose that "Yisachar" is a typo, and Rashi really wrote "Asher." But I don't think that is a good solution, because too many questions still remain:
1. Why did Rashi choose the names of the second children of the Shefachos?
2. In his presentation (later in this Dibur) of Achos Ishto, why does Rashi choose Naftali as the name for the father of all the 4 sisters, rather than Yisachar or any other name?
3. Earlier in this Dibur, by Achoso me'Imo, the mothers of Reuven and Shimon are Rachel and Bilhah - which is fine, since they are an easily recognized pair of co-wives (see (a) above). Why does Rashi change the mothers' names, in the case we are addressing (Eshes Achiv me'Imo), to Bilhah and Zilpah?
4. Where did Yachtze'el come from (in Rashi's presentation of Achos Imo)?
I can understand why Rashi chooses to discuss "Chel'ah and Na'arah, the wives of Kalev." Rashi poetically chose those names for his example of co-wives because the verse uses the term, "he had two wives," regarding Kalev's two wives, Chel'ah and Na'arah (Divrei Hayamim I 4:5 - although the verse ostensibly is discussing the brother of Kalev, the Gemara in Sotah 12a explains that it is just using another name for Kalev). The same goes for Adah and Tzilah, who Rashi also uses here (see Bereishis 4:19 - the only other place I could find where scripture uses the term "he had two wives" is by Elkanah, Shmuel I 1:2). Nachshon was chosen since he was a close relative of Kalev (Kalev's nephew) who bore a familiar name. But where did Yachtze'el come from? (None of the commentaries I saw addressed any of these points.)
The only answer I can think of is that Rashi had some reason to prefer Naftali over the rest of his brothers. He therefore used his name when looking for a new name after the names Reuven, Shimon, Levi and Yehudah (the standard four brothers of all the cases of Rebbi Chiya). That is why he chose Naftali in the case of Achos Ishto (question 2.). And that is why he used Naftali as the additional child in the case of Eshes Achiv me'Imo (your question and question 1.). That is why that child's mother became Bilhah (mother of Naftali), leading logically to choosing Zilpah as her co-wife (who bore "Yisachar" - reverting to the default pattern of Leah's sons), answering question 3. And, in the case of Achos Ishto (question 4.), since the father could not be named Yakov (he is the father of Revuen and brothers), nor could he be named Naftali (since he is from the generation above Revuen et al in this case, and calling him Naftali would lead to confusion), Rashi used the name of Naftali's oldest son, Yachtze'el (Bereishis 46:24).
But why was Naftali Rashi's "favorite" Shevet? Did Rashi choose him to father the girls of all these cases because Shevet Naftali was known to have more girls than any of the other Shevatim (Rabeinu Bachye to Bamidbar 1:20, Ba'al ha'Turim to Bamidbar 1:42)?
The best suggestion I could come up with is that Rashi presented an original explanation of his own for the meaning of Naftali's name (see Rashi to Bereishis 30:8). Because he associated his Chidush with Naftali's name, "Aidi d'Chaviva Lei, Akdemei" (see Yevamos 2b).
I hope that you find this helpful.
Kollel Iyun Hadaf