יֹ֣אבַד י֭וֹם אִוָּ֣לֶד בּ֑וֹ וְהַלַּ֥יְלָה אָ֝מַ֗ר הֹ֣רָה גָֽבֶר׃
나의 난 날이 멸망하였었더라면, 남아를 배었다 하던 그 밤도 그러하였었더라면,
Akeidat Yitzchak
In Niddah 16, Rabbi Chaninah ben Papa explained that the angel in charge of pregnancy is called "Laylah," night, since we read in Job 3,3, "And laylah said a man has been conceived." The angel takes a drop of semen, presents it in front of the Almighty and asks in His Presence, "What shall become of this drop? A wise man or a fool, a rich man or a poor man, a strong one or a physically weak one?" He does not ask whether the person will be righteous or wicked. This is in accordance with the dictum taught by Rabbi Chaninah that "All is in the hands of heaven except fear of heaven," since the Torah has said, "Now O Israel, what does the Lord ask of you except to fear Him etc." (Deut. 10,12-13).
Akeidat Yitzchak
Jacob's request to know the angel's name means that he wants to know who has the power to inflict this damage on his hip joint. The angel tells him that it is not the name that matters, since the ability to inflict damage was not rooted in the personality (name) of the angel, but rather it is an angel's mission that is of importance. Just as to many people the names of individual kings such as Saul or Hezzekiah or even David become blurred, and all they remember is that all these were Kings of Israel, so the individuality of an angel pales into insignificance when compared to his respective function. It had been Jacob's name (the crooked one) which had misled the angel into thinking that he was possessed of a fatal character flaw, and this is why he rectified his error by admitting that Jacob was indeed an Israel, a fighter for spiritual values. In consonance with the Rabbis' maxim that a hint to the wise is sufficient, the angel did not elaborate on the theme. Now that Jacob had done everything humanly possible on his own and his family's behalf, the first signs of Divine assistance become evident, commencing with the sun "shining for him," i.e. healing the physical affliction to the point where he could at least limp. (8) Apparently, up to that point he had been unable to move at all, and the dislocation of his hip joint had left him rooted to the spot of the nocturnal encounter. Since Esau's spiritual counterpart had not been able to find any other weakness in Jacob, the Jewish people, ever mindful of this weakness and convinced that this part of the body was more prone to sinfulness than any other part, abstained from eating that part of an animal, and even extended the prohibition to include use of the sinew for any purpose other than eating. Isaiah 48,4 uses the hyperbole of the sinew to describe sinful obstinacy per se. So does the prophet Micha in Chapter 4 verse 6. When Jacob experienced Divine assistance, he felt so reassured that he proceeded to face Esau without bothering to actually divide the camps. He was certain that now everyone could face Esau.