By Rabbi Amiram Markel
On the verse, “He smelled the scent of his clothes and blessed him, and he said, ‘See, the scent of my son is like the scent of a field that has been blessed by HaShem’”, Rashi comments, “There is no smell worse than the scent of unworked goat hides. However, this teaches us that the scent of the Garden of Eden entered with Yaakov.” This scent inspired Yitzchak with Ruach HaKodesh-the Holy Spirit and he blessed Yaakov.
Afterwards, when Esav came and Yitzchak realized that he had not blessed Esav, the verse states, “Yitzchak was seized by a very great fear and said, ‘Who then hunted the game and brought it to me. I ate from everything before you came and blessed him. Moreover, he will continue to be blessed.’” Rashi comments that when Esav entered, “Yitzchak saw Gehenom-Hell open up under him.” Commenting on the verse, “This must be why he was called Yaakov, because he has outwitted me (Yaakvaynee) these two times, first he took my birthright and now he has taken my blessing”, Rashi states, “Why was Yitzchak gripped with fear? He thought to himself, ‘Maybe I am guilty of a sin because I reversed the correct order and blessed the younger one instead of the older one who by birth should have gotten the rights of the first born.'”
However, when Esav cried out, “He outwitted me these two times,” Yitzchak asked him, “What did he do the first time?” Esav answered, “He took my birthright.” Yitzchak responded, “But that is exactly what I feared! I thought that I had transgressed the Halacha by not giving the blessing to the first-born. Now I realize that I did bless the first born and he will continue to be blessed.” In other words, with this new revelation, that Yaakov indeed had the rights of the firstborn, Yitzchak realized that the reason he beheld Gehenom when Esav came in, was not because he had sinned in blessing Yaakov, but because of Esav’s wickedness.
However, the question remains. Yitzchak said the words, “Moreover, he will continue to be blessed”, before he knew that Yaakov was the rightful recipient of the blessing. On the contrary, he said it specifically when he was gripped with fear that he had blessed him erroneously. If he thought it was a mistake why didn’t he reverse it and curse him instead?
The Klee Yakar explains that since Yitzchak gave over the power to bless or curse to Yaakov, when he said, “Whoever curses you will be cursed and whoever blesses you will be blessed”, therefore, now that it was in Yaakov’s possession, it was no longer Yitzchak’s to take back. It may also be explained in the following way. When Yitzchak blessed Yaakov with these words, it became an ironclad blessing that could not be taken back, because now, if he would curse Yaakov, the curse would revert right back to Yitzchak himself. This is why he said, “I ate from everything and blessed him. Moreover, he will continue to be blessed.” In other words, “I have no way to reverse this blessing.”
May it be HaShem’s will that all who curse the Jewish people shall be cursed and all who bless them shall be blessed, and may we behold the full culmination of the blessings that Yaakov received from his father Yitzchak, with the true and complete redemption through our righteous Moshiach. Amen.
 Genesis 27:27
 Genesis 27:33
 Genesis 27:36
 Genesis 27:29