וישלח-Yaakov Dances with the Devil

At the start of the Parsha, Yaakov is preparing himself and his family for the reunion with Esav, 20 years after he escaped his parent's home and Esav's wrath. Yaakov is afraid of the ramifications of this reunion, and is terrified once he learns that Esav is coming to greet him with an Army of 400 men.

According to Rav SR Hirsch, the root of the word ויצר is not צור or צרר, which are the Hebrew words commonly used to described sadness (as in Tsarot or Tsuris). ויצר, per Hirsch is from the root of the word "shape" (צורה) or "narrow" (צר). Yaakov felt his entire world closing in and that he was entirely at the mercy of Esav. That Esav had the power to "shape" Yaakov and his family into whatever form he wished, much like a craftsman shapes the material into whatever design he chooses. Yaakov's action of splitting his camp into two parts for preservation purposes set a precedent which the Jews followed throughout history. The Jewish people, per Hirsch, were able to survive the ravages of history since we were always dispersed. So when Jews were being killed in the West, the Jews in the East prospered.

As Yaakov is moving his camp into place for the reunion with Esav, he is left alone while he checks to see if any small items remain. Yaakov Avinu made his money the hard way and according to the Mefarshim was not going to leave anything behind, even the smallest item. The angel who wrestles with Yaakov, according to Rashi and some of the other Mefarshim, was none other than Satan (aka the angel of death, aka the Yetzer Hara).

According to the Kli Yakar, the Yetzer Hara felt that the opportunity was ripe to try and seduce Yaakov into doubting his beliefs in Hashem. Why was the opportunity ripe? Yaakov's love of money. Torah and money, per the Kli Yakar are diametrically opposed values and since Yaakov went out of his way to collect sundry items from the old camp, the Satan felt that now was the time to act. But Yaakov's belief in Hashem was too strong and the Satan gave up. But not one to give up easily, the Satan touched the socket of Yaakov's thigh (כף הירך) which is a hidden part of the body. This signifies that the Satan wanted to block Yaakov's access to the hidden parts of the Torah which can only be revealed to a privileged few.