Genesis 32:6

He cometh to meet thee. That Esau was attended by 400 armed followers is evidence that he had become a powerful chieftain. Perhaps he had already begun to live by the sword (ch. 27:40).

If Esau’s enmity toward his brother had softened during the years, it seems that he never mentioned the fact to his parents, with the result that Rebekah had been unable to fulfill her promise of sending for Jacob (ch. 27:45). The latter’s uncertainty as to his brother’s state of mind, and anxiety occasioned by the report of the messengers, alarmed him in the extreme. Esau’s reason for going to meet Jacob with such a company was, first, to impress Jacob with due respect for his superior power, second, to ensure a satisfactory understanding, and third, to use force if necessary to safeguard his own interests. He was prepared, in other words, for any eventuality.