Genesis 27:33

And Izhak was moved with great agitation when he heard the voice of Esau, and the smell of his food rose in his nostrils as the smell of the burning of Gehennam; and he said, Who is he who hath got venison, and come to me, and I have eaten of all which he brought me before thou camest, and I have blessed him, and he shall, too, be blessed?

AND ISAAC TREMBLED VERY EXCEEDINGLY, AND SAID, WHO THEN IS HE THAT HATH TAKEN VENISON AND BROUGHT IT TO ME, AND I HAVE EATEN OF ALL BEFORE THOU COMEST AND HAVE BLESSED HIM? YEA, AND HE SHALL BE BLESSED. It is not natural for a person who just trembled violently and complained, “Who was it that subtly made me bless him?” to conclude his complaint by immediately saying, Yea, and he shall be blessed! Rather, it would have been proper that he curse him! Moreover, Esau would then complain to his father, saying, “But why do you bless him now, my father?” And how would Esau believe his father that it was originally done through subtlety when he saw that he was now blessing him willingly!
The correct interpretation appears to me to be that it is in the present tense., generally understood as a future tense — and he shall be blessed — is here to be understood as a present tense, as explained below in the text. Isaac is saying, “Who then is he that hath hunted venison, who could have beguiled me so that I should bless him and that he should remain blessed under all circumstances for I knew that he is a blessed one?” Or it may be that the expression, Yea, and he shall be blessed, means “against my will, since it is impossible for me to transfer the blessing from him.” From the moment he blessed him, Isaac knew by Ruach Hakodesh that his blessings indeed rested upon Jacob. This then is the reason for his violent trembling for he knew that his beloved son Esau had lost his blessing forever. This also is the explanation for his saying, Thy brother came with subtlety, meaning that after he said, Who then is he etc. he realized that Jacob had been the one who came before him to receive the blessing for it would have been impossible for the blessing to rest on any but his offspring, [and, as mentioned above, Isaac knew by Ruach Hakodesh that the blessing had taken effect. Hence he was sure that it was Jacob who had come before him.]

ויחרד יצחק, he was upset at having found hair on the smooth part of Yaakov’s neck.

מי איפוא, this is a turn of phrase, as is the word איזו in the Talmud Baba Metzia70 אימא לי איזו, “tell me my dear friend.”

גם ברוך יהיה. “Because he carried out my request so promptly.” Also, Yitzchok was aware that Yaakov had done what he did at the advice and request of Rivkah. Clearly, he reasoned, Rivkah had realised that Yaakov was entitled to this blessing.

?מי איפוא הוא, if it is indeed true that you are Esau, who was the one who served me venison? When the word איפוא appears with the letter א at the end, the word is an alternative for the two words אם כן, “if so.” When the same word (phonetically speaking) is spelled with the letter ה at the end, as for instance, in Genesis 37,16 איפה הם רועים?, the word means the same as איה, “where?”

גם ברוך יהיה, the appropriate translation of the whole verse would be: “if this is so that you are indeed Esau, who is the one who brought me the venison and still achieved that he will remain blessed?!” Yitzchok had felt instinctively at the time he had bestowed the blessing that it would become fulfilled for the person whom he was blessing at the time. This confirms something told us by Rabbi Chanina in Berachot 34 that whenever he prayed for the recovery of a sick person he could feel while praying for him if his prayer would be effective.

ויחרד; he displayed his emotional upset in front of Esau in order that Esau should not think he had deliberately fooled Esau by blessing Yaakov. He said:

מי איפוא, the words mean: “who is he, and where is he now?”

ואכל מכול, of all the tasty dishes which he served me.

בטרם תבא, “before you could come. If I had not eaten of all the type of food he had prepared for me, and you would have arrived while I was in the middle of eating, I would have stopped eating from his food and have helped myself to yours and have blessed you. However, since I have eaten my fill before you came I cannot do this now since I have blessed him already.”

גם ברוך יהיה, since I have already blessed him I confirm my blessing for I knew that he was my son (not an outsider).

ויחרד יצחק חרדה גדולה עד מאד “Yitzchok was overcome by an exceedingly strong trembling;” Yitzchok actually experienced two separate fits of trembling; the first time had been when he lay bound on the altar of Moriah, expecting to have his throat slit. The second time occurred here. (B’reshit Rabbah 67,2). He asked himself what sin he had been guilty of, so that he had blessed the younger son before he had blessed the older son. He had caused Esau to groan, complaining (if I had no blessing left for him). Our author quotes a line in our version of Rashi, that did not appear in some later editions, such as the ones relied on by Luzzato.

מי איפוא, “who and where?” Yitzchok questioned himself who was now destined to wind up in Gehinom, either he himself, or Yaakov for using deceit, or Esau for having used deceit for all these years? The words following are the ones provided from the Holy Spirit, stating clearly that he who had “hunted venison”, (metaphor for deceit, as animals must be lured to their death by deceit). Hearing this, Yitzchok continued