Why does the Torah see fit to tell us that Timna was the concubine of Esav's son, Elifaz (even though it does not name the wives of Esav's other sons here)?
Rashi and Ramban #1: To teach us the greatness of Avraham Avinu. Timna (who was the daughter 1 of one of the chiefs who initially resided in Har Se'ir 2 ), decided that it was preferable to become a concubine in the family of Avraham than a wife among her own people, and ended up as the concubine of Elifaz. 3
Seforno: Elifaz, who was among the conquerors of Har Se'ir, took her as a concubine by force (as she was the daughter of one of the chieftains).
Ramban #2: Because Elifaz' son, Amalek, was born to him from Timna, who was a concubine, he is not included in the Bnei Esav, 4 nor did he dwell together with them in Har Se'ir. 5
See 36:22.
Oznayim la'Torah: And in a supreme twist of irony, which can only have come about by Divine Decree, that, whenever Yisrael want to go astray and break their link with Hakadosh-Baruch-Hu, it is Amalek, the son of this refined woman who sought to join the family of Avraham because she appreciated its nobility of character, who makes propaganda among the nations of the world not to allow the lowly Jews to mix with them!
In the same way as his grandfather (Avraham) separated Yishmael from Yitzchak (See Bereishis 21:10).
Ramban: Consequently, the prohibitions against hating Edom and taking possession of their land (Devarim 23:8; 2:5) did not extend to Amalek - whom we were subsequently commanded to abhor and to erase their name (Devarim 25:17-19).
How does this tally with the Pasuk in Divrei ha'Yamim I (1:36) that lists Timna among the children of Elifaz?
Rashi: In fact, Elifaz committed adultery with the wife of Se'ir ha'Chori, 1 who bore him Timna and whom he subsequently took as a concubine. 2
Ramban #1: Elifaz married the wife of Se'ir ha'Chori after he died, and she bore him Timna, whom he subsequently married. 3
Ramban #2: There were two Timnas, one mentioned here, the other, in Divrei ha'Yamim (which is synonymous with the Timna mentioned later in 36:40), both of whom were Mamzerim. 4
Ramban #3, Moshav Zekenim and Rashbam, from Midrash Sechel Tov: Elifaz had a son named Timna, 5 and also a concubine named Timna.
Ramban #4: After giving birth to Amalek, Timna, the concubine of Elifaz, bore a son and died in childbirth. Before she died however, she called him Timna, to perpetuate her name, but Elifaz called him Korach. 6
Refer to 36:16:0.2:2.
One can assume that Targum Yonasan, (according to whom Elifaz was Iyov's friend, a Navi) will not concur with Rashi's explanation.
See Sifsei Chachamim.
Since a ben No'ach is permitted to marry his daughter. The Torah therefore does not mention her among the children of Se'ir, since her father was not from the family of Se'ir (Rashi). Refer also to 36:22:1:3.
Sechel Tov: Why was Timna not listed among Elifaz' sons? Indeed, the word "v'Simna" at the start of our verse is read also with "u'K'naz" (at the end of 36:11), in the list of Elifaz' sons. The Pesik (line) between "v'Simna" and "Haysah" alludes to this. Rashbam and Moshav Zekenim cite other examples of words like this that are interpreted as double. Ramban - The Torah did not want to write Timna twice, for a male and for a female. Also refer to 36:16:0.2:4.
See Ramban. The Rashbam too, equates Korach with Timna mentioned in Divrei ha'Yamim.
QUESTIONS ON RASHI
Rashi writes: "'Timna was a concubine' - This teaches the greatness of Avraham, to what degree [people] desired to join with his offspring." But perhaps Timna is mentioned only to teach that Elifaz fathered chieftains even from his concubine?
Gur Aryeh: While it is true that Timna is the only mother of Esav's grandchildren mentioned by name, the verse could have sufficed by saying, 'And his concubine, her name was Timna' (as it does in 22:24). [Rather, it implies, 'Timna sufficed with becoming a concubine' to Elifaz, for he was descended from Avraham.]
Rashi writes: "[Timna] said, [if] I do not merit to be married to you...." Chazal (Sanhedrin 99b) teach that Timna came before each of the Avos to convert, and they did not accept her. Why not?
Maharal (Chidushei Agados Vol. 3, p. 229, to Sanhedrin 99b): A convert must be able to connect completely with [the court] that converts them. The Avos humbled themselves before Hashem. Timna would not be able to lower herself, for she was a princess.
Rashi writes: "[Timna] said, [if] I do not merit to be married to you; if only I could be a concubine!" Chazal (Sanhedrin 99b) teach that Amalek, who would torture Yisrael, came about as a result -- for the Avos should not have distanced her. Why was Amalek the result?
Maharal (Chidushei Agados Vol. 3, p. 229, to Sanhedrin 99b): We see that of all the nations, only Amalek has such hatred for Yisrael. (It is upon Yisrael that all the rest of creation depends! 1 ) The Avos of Yisrael actively distanced Timna (by rejecting her); and as a result Amalek has no attachment whatsoever to Yisrael.
The other nations somehow sense this, and do not try to wipe us out outright.
Rashi writes: "But in Divrei ha'Yamim I (1:36), Timna is listed among the children of Elifaz. It must be that Elifaz lay with Se'ir's wife, and Timna thus came about from among the two of them. When she grew up, she became Elifaz' concubine." Ramban asks - If that is true, why would Elifaz' daughter be inserted in the list of his sons?
Gur Aryeh: Since the verse in in Divrei ha'Yamim I (1:36) wishes to list Amalek, it must list his mother Timna first.
Rashi writes: "It must be that Elifaz lay with Se'ir's wife... When she grew up, she became Elifaz' concubine." But perhaps there were two different Timnas?
Gur Aryeh: Divrei ha'Yamim I (1:36) lists Timna among the children of Elifaz. Yet, unlike the other children of Elifaz, Timna is not listed among Esav's chieftains (Bereishis 36:15-16)! It must be because Timna was a woman [ - the same one as mentioned here].
Rashi writes: "It must be that Elifaz lay with Se'ir's wife...." But perhaps he married her legitimately, after Se'ir died?
Gur Aryeh: Timna is mentioned among the offspring of Se'ir (36:20). She is only relevant to that verse if people thought she was Se'ir's daughter; i.e. Se'ir was still alive, and Elifaz committed adultery with his wife.
