When the Jewish people were on the banks of the red sea the verse tells us "the Israelites lifted up their eyes, and behold! the Egyptians were chasing after them, and they were very frightened, and the Israelites cried to Hashem". My father my master of blessed memory explained that they weren't frightened of their armies per se, because they had seen with their very own eyes amazing miracles and death of the first born in which many died in a single moment. G-d could do this as well to the armies which confronted them to kill them all in one moment.
However, their fear did grow when they saw the Egyptians chasing after them, as Rashi explains "with one heart, like one man". The very fact that they were united expresses a positive spiritual force, as the forces of evil are always seperate leaves. When the Israelites saw the Egyptians saw them united in this way, then they were frightened because they they thought that they now have a level of holiness about them.
That may have been true, but the reason for their unity was precisely to arouse the hearts of the Israelites into prayer....
With this in mind in our subject. The verse tells us that there were 400 men with him.
The language of "ISH" (rather than ANASHIM) expresses the same idea - Esau's 400 men showed they were completely simpatico with his views with one heart.
It is for this reason that we can understand why Jacob according the Medrash believed that Esau was coming with the strength of his service for his father, or that he lived in Israel, which would account for the level of unity which he saw. It is for this reason that he was frightened.
With this we can also explain what it means when it says that "Jacob was anxious". My father of blessed memory explained that it known that the portion of Jacob is one without any borders*, and the nations of the world, and the evil forces don't have the capacity to drain that from him.
When he saw his brother moving towards him with this powerful force he thought the reason for this is because Jacob himself instigated this all by sending messengers to him in the first place, increasing Esau's sense of arrogance. This is the essence of Mitzrayim (Egypt which shares the same root as Mitzarim meaning boundaries as above*) whose evil is drawn from those around it.
We could explain this phenomena in a different way according to another of my father's words on the Medrash Esther, where it says "in those days when the king sat on his throne" the angels were complaining to the Almighty: the temple is destroyed, and this evil man is sitting and making festivities. G-d replied that it grew out of the desecration of Shabbos. My father explained that the question of the angels as as follows: if the temple is destroyed, and it is the joy of the world. If so, where does this wicked King (Achashveirosh) find rest and joy as he celebrates?
Hashem replied that it stemmed from the desecration of the Shabbos. The definition of Shabbos is rest, and when the Jewish people blemish that rest G-d forbid, the nations of the world take it away for themselves.
According this, when the Egyptians were chasing after the Bnei Yisrael in a unified state. The Jews only find that level of unity at Sinai. However, all their other encampments were in disagreement and arguement.
The matter is difficult - why should they have been arguing with one another at all - they didn't at the time have any businesses in the desert. Each one had vast wealth... our rabbis of blessed memory say that each Jew who didn't have 90 donkeys loaded with the silver and gold of Egypt.
Furthermore, the joy of having left Egypt should have prevented any arguments. It is known that when a person is experiencing joy they can even bear dealing with their enemies! Logically the Bnei Yisrael should have constantly experienced complete unity. However, it was the opposite, and not only that, but the Egyptians themselves took that unity for themselves. In the vein of (my father's explanation) Jacob wondered how it was possible for this unity to come to Esau with his 400 men - it must be the result of the fact that there was a blemish in his unity.
This notion is something we have spoken about elserwhere; that all of existence and experience. even negative experience comes from G-d's true existance. It all stems from the concept of "There is nothing besides Him"...
This is because Hashem minimises Himself until it appears that there is something that is able to stand up against holiness. However, since this comes from a place of HESTER PANIM (G-d hiding himself within physical reality), that negativity won't have control over a person who is in unity with the Almighty.
The Ramban writes that Yaakov was frightened of some sin that he had committed when he entered into a covenenant with Lavan. We could also postulate on the basis of this Ramban that Yaakov sinned when he called Lavan's brothers his brothers. (He created a false sense of unity when none existed)....
Therefore, Jacob was worried that because of the brotherhood that he had created with Lavan's people his own sense of unity.
There is also something else to add that Jacob thought of himself as a sinner because he was frightened of his brother. He should have known because of the unity of the Almighty, no-one is able to stand against His will. Therefore being frightened to the extent of having to send messengers to Eisav, or having a covenenat with Lavan's family caused a blemish in the Almighty's unity, and that unity was therefore taken by Eisav. This why he says "VAYEITZER LO" - he had boundaries, because a true belief in G-d does not create any boundaries.
Rabbi Shimshon Refael Hirsch
We could imagine ourselves in Jacob's feet. We are very obligated to do this when we take into account the importance of the impending meeting.
Just like Jacob and Esau stand opposite to one another, so they continue to stand to this very day. Jacob is the family man who is blessed with children, who is involved in his work with industry, and the worries that are heavy about his throat.
Esau on the other hand is the complete man "from העשוי".
Jacob returns now as the head of an independent family. Even now, after he has overcome all the traps (of Laban), this level is considered to be something great from his perspective for him .However, in order to achieve this status he has had to labour and struggle 20 years, despite receiving the blessing of Isaac.
However, from a different perspective, the merit to have a family and to support them is something which is a given from birth for Esau. Esau, "this perfect and made man" achieved this (family; being able to support them) achieved this in an accentuated way from the moment that Jacob got up and left the house. While Jacob was successful in his hard work to set up a family, Esau was able to become a political force, the leader of an army and general at the head of his troups.
Such is the comparison between Jacob who holds onto his brothers heal at birth, and Esau, the perfect man.
With these two men, there are two essences which oppose each other; the struggle between them and its result are the powers that have influenced more than anything else in the world. Jacob exemplifies a family life, wealth, and bringing of wealth to someone else; while Esau exemplifies the shining of strength and political independence. This struggle has taken place for thousands of years: is it enough for a man to just be " a man" who doesn't have political strength; versus a person who takes everything in his own personal life, his purpose for some political control?
How different is the standing of Jacob against Laban then against Esau? We know the strength of someone who trusts his uprightness, and yet however much this element exist doesn't influence feelings of guilt (placed upon him by Esau), even if it is imagined. It is easier to bear ill treatment and lack of justice for more than 20 years; then to stand one second face to face against a person who we know we have dissappointed, someone who is unable to understand our motives, even if we are not saying that they are correct, but rationalising them.
"Jacob was frightened" even though he had been promised that G-d will take care of him. From here our sages learn that "there is no promise for the righteous in this world". Every promise given is on condition that the righteous person acts in a constant righteous manner; they can lose at every moment, if the person loses that constancy and acts in an imperfect way.
"perhaps sin will cause negativity in thier lives" - is a worry that never leaves the greatest of the great.
The word of Vayeiter loh - doesn't mean that he felt confined, rather it was that he had been formed into a certain shape, and was unable to move..... So Jacob felt when he stood against Esau, and we still find ourselves in the exact same situation for hundreds of years. In this situation, the goodness of our lives, our children and wealth is not the arbiter and leader; rather they are dependent upon the kindness of others and their purposes, and we have to suffice with the crumbs that fall by chance from their tables.
Jacob felt that he was completely placed under the kindness (and thumb!) of Esau, which comes towards him with 400 men. It is because of this that he divides the people into 2 camps, to ensure some sort of survival.
So too now, in our dispersal in the diaspora is the secret of our success and survival. In no place and time could the sword of Esau reach all of us in one time. When blood was spilled in the west, our brothers in the east were safe, and visa versa.