Matthew Poole and continuators on Genesis 27:4

4 And make me favoury meat, such as I love, and bring it to me, that I may eat , that my soul may bless thee before I die.

Quest. Why doth he require this before he bless him? Answ. 1. That being refreshed and delighted therewith his Spirit might be more chearful, and so the fitter for the giving of this prophetical benediction; for which reason also the Prophet. Eliha called for a minstrel ere he could utter his Prophesie, 2 Kings 3. 15. 2. By the special direction of Divine providence, that Esaus absence might give Iacob the advantage of getting the blessing.

He speaks not here of a common and customary blessing, which Parents may bestow upon any of their Children as and when they please, but of the last, solemn, extraordinary and prophetical benediction, whereby these holy Patriarchs did by Gods appointment and with his concurrence constitute one of their sons heir not onely of their inheritance, but of Abrahams covenant and all the promises both temporal and spiritual belonging to it. As for the oracle delivered to Rebecca which transferred this blessing upon Iacob, chap. 25, 23. either Isaac knew not of it, not being sufficiently informed thereof by Rebecca; or he did not throughly understand it; or he might apprehend that it was to be accomplished not in the persons of Esau and Iacob but in their posterity; or at this time it was quite out of his mind, or he was induced to neglect it through his passionate affection to his son Esau.