Why are Bnei Yisrael forbidden to eat the Gid ha'Nasheh (the sinew on the spoon of the thigh)?
Seforno: To belittle the damage that occurred, that it was not on something important to us. 1
Rosh, Da'as Zekenim #1, Hadar Zekenim #1, Riva #1, Moshav Zekenim #1: Because [Yaakov's sons] let him go alone, and he was harmed, they lost this nice food 2 forever, 3 to recall their sin. 4
Hadar Zekenim #2, Riva #2, Moshav Zekenim #2: They accepted not to eat it. 5
Da'as Zekenim #2, Hadar Zekenim #3, Moshav Zekenim #3: It commemorates the miracle, that the angel did not kill Yaakov and only harmed his thigh.
Ohr ha'Chayim: It is because the Gid was moved from its place of Kedushah, and Kelipah (a shell of Tum'ah) ruled over it everywhere (also in animals). This is why it has no taste 6 !
Malbim: One who eats meat, it become part of him. The Torah forbids Tamei species, because the eater can acquire their cruel nature. Even though Yaakov was separated from all physicality, the angel was able to harm it - this shows that it is tied to lust and physicality. The Torah forbids eating it, to remind us to separate from physicality and be Kadosh to Hashem.
Ha'amek Davar: It is to remind us how to deal with those who rise against us. We should not contest them too much, nor be too obstinate. Once the fear departs, we should let the pursuer go away.
Maharal: Refer to 32:33:2.1:1; 32:33:2.2:1.
I do not understand this. There are vital parts of people (bones, brain, heart, eyes...) that we do not normally eat in animals! (PF)
We hold (YD 100:2) that the sinew has no taste! However, Yisrael are stringent not to eat the fat of the sinew, and after removing it, the thigh does not look so nice. (PF)
Moshav Zekenim asks that if so, we should not eat eyes, for Yitzchak's eyes were stricken! (Seemingly, that was not due to the sin of Yisrael! - PF)
Da'as Zekenim: This will make them careful to escort, like Yaakov was careful to escort Yosef when he sent him to his brothers, and both were not punished (Hadar Zekenim). Chulin 91a learns from this episode that a Talmid-Chacham should not go out alone at night.
Hadar Zekenim, Riva: This was so that in this merit Yaakov would be healed. Moshav Zekenim - even though he was healed, he warned them not to be harmed similarly. Alternatively, it is like one who fasts on the day [of the year] that his father died.
Also permitted Gidim have no taste! (R. Yehudah forbids only the right Gid (Chulin 89b). Surely it has no more taste than the left Gid! - PF)
Why is it called 'Gid ha'Nasheh'?
Rashi: It Nashah (moved) from its place and jumped up (became dislocated). 1
Rashi: As in Yirmeyahu 51:30, and Bereishis 41:51.
Why is the Gid ha'Nasheh forbidden to all of Yisrael forever, because of an event that happened to Yaakov?
Maharal (Chidushei Agados Vol. 4, p. 104, to Chulin 91a): Yaakov was the root of the Jewish People, and whatever applies to the roots applies to the branches as well. 1
This can be said of all of the Avos; refer to 15:13:4.2:1 and 24:42:3.1:1.
What is the Shi'ur Chiyuv for eating Gid ha'Nasheh?
Chulin 96b: One is Chayav for eating a complete Gid ha'Nasheh - a Beriyah - however one is liable for a k'Zayis even if it is not complete, since the Torah writes "Lo Yochelu," and the Shi'ur for eating is always a k'Zayis.
May one benefit from Gid ha'Nasheh?
Torah Temimah (citing Pesachim 22a): Even according to R. Avahu, that we say that wherever the Torah writes "Lo Yochal... " it forbids also benefit, one may benefit from Gid ha'Nasheh. When the Torah permitted Nevelah b'Hana'ah, it also permitted the Chelev and the Gid ha'Nasheh in it. 1
They are permitted in every case. A Mishnah (Chulin 7:2) permits sending a thigh with Gid ha'Nasheh to a Nochri. (PF)
To which species of animal does the Isur of Gid ha'Nasheh apply?
Chachamim (Chulin 100b): It applies to all Tahor species of animals exclusively. 1
R. Yehudah (Chulin 100b): It applies even to Tamei species of animals. 2
Chulin 101a: This is because the Torah attributes the Isur to the Gid. The Gid of a Tamei animal is already forbidden, together with the entire animal!
Chulin 101b: This is because it was forbidden before Matan Torah, when there was no distinction between Tahor and Tamei. Chachamim hold that it was permitted until Matan Torah (since the Torah writes [not 'Bnei Yaakov,' but rather] "Bnei Yisrael;" for Mitzvos, they adopted this title only at Har Sinai, which is where this Pasuk was said. And it is written here only in order to explain why the Gid ha'Nasheh became forbidden.)
The Tana'im (Chulin 91a) dispute whether only the right Gid ha'Nasheh is forbidden, or the left one as well. What is the basis for this?
Maharal (Chidushei Agados Vol. 4, p. 103, to Chulin 91a): They disagree as to whether one of Yaakov's thighs was injured, or both. Refer to 32:26:2.1:1 and 32:26:2.1:2 for more elaboration.
What is the law regarding the Gid ha'Nasheh of an Olah?
Chachamim, Chulin 90b: The thigh is taken complete onto the Mizbe'ach, and Kohanim remove the Gid and toss the Gid on to the Tapu'ach (the pile of burnt-out ashes in the middle of the Mizbe'ach. 1
R. Yehudah, Chulin 90b: The thigh is burned intact, with the Gid.
Because we serve Ha'Kadosh-Baruch-Hu only with what is permitted to a Yisrael - See Torah Temimah, 19.
What are the implications of the words "Al Kaf ha'Yarech"?
Chachamim (Chulin 96b): "Al Kaf" preclude the section of the Gid that is not lying on the spoon of the thigh. "Ha'Yarech" is the inner Gid; it excludes the outer Gid.
R. Yehudah (Chulin 96b): One is liable only for "Al Kaf" (the section of the sinew on the spoon of the thigh).
What does the Torah mean when it writes, "Ad ha'Yom ha'Zeh"?
Rashi (26:33): It refers to anyone who reads the Pasuk at any time in the future.
QUESTIONS ON RASHI
Rashi writes: "It is called Gid ha'Nasheh, for it jumped and moved up from its place." How does this explain why it is it forbidden?
Maharal (Chidushei Agados Vol. 4, p. 104, to Chulin 91a): When something deviates from its state of equilibrium, to either extreme, it becomes forbidden.