Musar for Micah 7:8

And one who trusts God should hold on during the vision of his distress; for the darkness will be the cause for the light - as it is written (Micah 7:8), "Do not rejoice over me, O my enemy; since I have fallen, I rise again; since I sit in darkness, the Lord is my light." And our Rabbis, may their memory be blessed, said (Midrash Tehillim 22), "If I had not fallen, I would not have risen; If I had not sat in darkness, the Lord would not have been my light." And every single person on the day of his trouble should put into his heart to understand and afflict himself, [together] with the repentance and prayer - just like the community is obligated to fast and afflict themselves at the time of their trouble, as the Sages, may their memory be blessed, ordained. And that fast day is chosen and is a day of acceptance. And when the rebuke of God, may He be blessed, comes to a man that is pure and straight, it becomes a test, and enhances his reward in the world to come - as it is stated (Deuteronomy 8:16), "in order to test you by hardships only to benefit you in the end." And our Rabbis, may their memory be blessed, said (Berakhot 5a), "[If] one searched his deeds at the time of his trouble, sought out and investigated, but did not find a sin - these are certainly afflictions of love."

It is important for one who has trust in the Lord, Blessed be He, to know that the afflictions are for his own good, and in the end it will be well with him. As it is said, "Rejoice not against me, O mine enemy; though I am fallen, I shall arise; though I sit in darkness, the Lord is a light unto me" (Micah 7:8). And our Sages, of blessed memory, said, "If I had not fallen, I would not have arisen! And, if I had not sat in the darkness, I would not have seen the light!" (Shohar Tov 22:7). Therefore, any man who has troubles in his body, or with his money, or with his children, should set his heart to fast in addition to doing repentance, just as the community is obligated to fast in the time of their trouble, and as our Sages have decreed (Ta'anith 10a, 12b). Therefore, in time of trouble, a man should examine his deeds. If he has searched and has found no transgression, he should know that his afflictions have been prompted by God's love (Berakhoth 5a).

What all this has to do with Samael injuring the כף ירך יעקב, the thigh joint of Jacob, is simple. Our sages say on 32,26: וירא כי לא יוכל לו, ויגע בכף ירכו ותקע כך ירך יעקב, that the thigh joint of Jacob refers to the later descendants who experienced the harsh decrees by the various nations who were their hosts in exile. When the Hasmoneans overcame the Greeks, they reversed this injury, i.e. the כף became a פך a cruse of oil. What had been a vulnerable part of Jacob's ירך now became the solid basis of the candelabra, ירך מנורה.