Genesis 28:6

And Esau considered that Izhak had blessed Jakob, and had sent him to Padan Aram to take to him from thence a wife, when he blessed him, and commanded him, saying, Thou shalt not take a wife of the daughters of the Kenaanites;

וירא עשו כי ברך יצחק את יעקב, Esau realised that in the blessings which Yitzchok had given Yaakov the land of Canaan as his heritage had been included, and that Yitzchok also had given Yaakov specific instructions to get a wife from amongst the daughters of Lavan, the brother of his mother, and on no account to marry a local Canaanite girl. Esau therefore arrived at the conclusion that he had been deprived of his share in the land of Canaan as a penalty for having married Canaanite girls and that this was the reason why Yaakov had been successful in stealing the blessing of Avraham from him. He therefore decided to marry into Avraham’s family, i.e. a descendant of Ishmael. He thought to himself that perhaps by doing this he would restore his claim to Avraham’s heritage.

וירא עשו כי ברך יצחק, we see from here that in spite of Esau’s noting that his father had sent Yaakov all the way to Charan to prevent his marrying one of the Canaanite girls, as this was not in keeping with his blessing, he did not pay much attention to this, except that when he saw to what extent his father was unhappy about this כי רעות בנות כנען בעיני יצחק אביו, he thought that it was due to his wives opposing his parents’ lifestyles, etc., as documented I 26,35. In order to appease his parents he then went to Ishmael to marry Machalat. One of the reasons the Torah reports these details is to show that had Yitzchok objected to Esau’s marrying Canaanite girls in the first place his objection would have been effective. If Rivkah’s intervention was effective now when she remonstrated with her husband there is no reason to believe that it would not have been effective when Esau was about to get married.

וירא, seeing that the sense of sight is a more reliable sense of perception than any of the other 4 senses, the Torah describes Esau’s realisation of what had transpired as being visual.

לקחת לו משם אשה, the fact that Yaakov was fleeing from Esau’s wrath had not become known, everyone thinking he had left to select a bride for himself.