וַיִּוָּתֵר יַעֲקֹב לְבַדּוֹ וַיֵּאָבֵק אִישׁ עִמּוֹ עַד עֲלוֹת הַשָּׁחַר: וַיַּרְא כִּי לֹא יָכֹל לוֹ וַיִּגַּע בְּכַף־יְרֵכוֹ וַתֵּקַע כַּף־יֶרֶךְ יַעֲקֹב בְּהֵאָבְקוֹ עִמּוֹ
"And Jacob remained alone and a man wrestled with him till the dawn broke. And he saw that he could not overcome him and he touched the hollow of his thigh (Gid HaNashei), and the hollow of Jacob's thigh was out of joint while he wrestled with him" (Bereshith 32:24-25).
Yaaqob Abinu, 'a"h, wrestled with the Sar (angel) of Esau. The Sar of Esau hit Yaaqob Abinu, 'a"h, in his thigh and caused a dislocated hip. Because of this the Torah forbids us to eat the Geed HaNashei (the displaced tendon or sciatic nerve). The Sefer Hahinnukh explains that this commandment is a hint to us that even though Kelal Yisrael will suffer great pain from the nations and the children of Esau, nevertheless, we should be confident that we will not be overcome and lost, Heaven forbid. Rather, we will always keep standing and eventually our redeemer will come and redeem us from those that cause us pain. And we will remember it, through this Miswah (commandment).
We will also remember, that Esau's angel fought with Yaaqob Abinu, 'a"h, and wanted to uproot him and his children from this world. He failed, of course, but, nevertheless, caused him pain when he touched the hollow of his thigh. So too the children of Esau continue to cause pain to the children Israel, but, nevertheless, just like that the sun rose for Jacob and he was healed from his limp, so too, the sun will rise for the Jewish Nation and Mashiyah will redeem us from all the suffering. May this day come speedily, Amen.