עָשָׂ֨ה יְהוָ֜ה אֲשֶׁ֣ר זָמָ֗ם בִּצַּ֤ע אֶמְרָתוֹ֙ אֲשֶׁ֣ר צִוָּ֣ה מִֽימֵי־קֶ֔דֶם הָרַ֖ס וְלֹ֣א חָמָ֑ל וַיְשַׂמַּ֤ח עָלַ֙יִךְ֙ אוֹיֵ֔ב הֵרִ֖ים קֶ֥רֶן צָרָֽיִךְ׃ (ס)
여호와께서 이미 정하신 일을 행하시고 옛날에 명하신 말씀을 다 이루셨음이여 긍휼히 여기지 아니하시고 훼파하사 원수로 너를 인하여 즐거워하게 하며 너의 대적의 뿔로 높이 들리게 하셨도다
Akeidat Yitzchak
(6) Esau's concept of the birthright and its values may not have differed much from the way many Jews perceive the "feast of Leviathan." Some are willing to sell their claim cheaply, whereas others treasure it and would spend their life savings to assure themselves of their share in it. Since Jacob realized that although he treasured the value of the birthright, Esau considered it of trifling importance, he felt morally justified in swapping it for a nominal amount. The apparent urgency to complete the transaction (sell it to me this day!) may have been prompted by the realization that the next time Esau would be exhausted he might well be at the point of death, and the opportunity for this transaction might have disappeared forever. Since Esau had made it clear that he had many close encounters with death (Genesis 25,32), Jacob made it plain that under such circumstances, when no documents were at hand to record transfer of ownership, the least he required was an oral declaration of a binding nature. The sale was to become effective "as of now!" The Torah gives evidence that Esau had an opportunity to reconsider this rash decision when he was fully restored to his senses, i.e. after having eaten. Therefore, we are told, "He ate, he drank, he got up and he went about his business; he despised his birthright."