Or HaChaim on Genesis 25:34/אור החיים על בראשית כ״ה:ל״ד

1 ויקם וילך ויבז עשו את הבכורה, Esau arose, went on his way and despised the birthright. The Torah stresses that Esau's despising the birthright was a conscious act. Had the Torah written: "He arose, he went and he despised the birthright," we could have thought that he merely did so unconsciously. The Torah added the word "Esau" here once more to tell us that Esau deliberately showed disdain for the birthright. Even if Esau had not desperately needed to trade something to obtain some of Jacob's potage he would have sold the birthright cheaply at any time if Jacob had asked him to.