The fear that the enmity had continued was what frightened Jacob when, years later, he was on the way home and about to encounter his brother again. So he sent messengers to Esau to find out the situation and to bring a message of friendship.
They came back with a discouraging report: “We came to your brother Esau,” they said, “and he is on the way to meet you, and 400 men with him” (Gen. 32).
400 men represent a major hostile threat. Does the figure of 400 have any particular significance?
Since 40 comes many times in Scripture, ten times 40 is symbolic of a very large round number. No wonder Jacob was afraid: says Rashi, afraid that he might be killed, and afraid that he might have to kill.
Rashbam, however, takes a completely different approach. His suggestion is that the large number who accompanied Esau were not an attacking but a welcoming party: to show good will, Esau had brought a large retinue to do honour to his brother.
Then why does the Torah say that Jacob was afraid?
Because when the messengers reported that Esau had peaceful intentions, Jacob did not believe them and thought Esau still wanted revenge for the deceit he had practised on him when they were both young.
How did it all work out?
Nachmanides has an idea that marries the opposing views of Rashi and Rashbam. According to Nachmanides, Esau’s intention actually was hostile, but when he saw Jacob’s respectful behaviour and his modest deference, including the fact that he addressed him as “my lord”, implying that Jacob acknowledged Esau as the first born, Esau’s compassion was stirred and they met as friends.