"And Jacob said to Rebekah his mother, 'Look, Esau my brother is a hairy man, and I am a smooth-skinned man. Perhaps my father will feel me, and I shall seem to be a deceiver to him; and I shall bring a curse on myself and not a blessing.' But his mother said to him, 'Let your curse be on me, my son; only obey my voice, and go, get them for me.' And he went and got them and brought them to his mother, and his mother made savory food, such as his father loved. Then Rebekah took the choice clothes of her elder son Esau, which were with her in the house, and put them on Jacob her younger son. And she put the skins of the kids of the goats on his hands and on the smooth part of his neck. Then she gave the savory food and the bread, which she had prepared, into the hand of her son Jacob" (Gen. 27:11-17).
Rebekah persuades Jacob to proceed with the plan, and he does not resist too strongly! The food is prepared and the costume is complete. Jacob will do his best to trick his father into believing that he is Esau. And for what reason? To secure a blessing from the great patriarch! As a side note, it should be observed that the fact that Rebekah and Jacob stoop to this level implies a lack of total faith in God's promise. The LORD had already affirmed that "the older shall serve the younger" (25:23). Did they really think they needed to lie and deceive in order to make it come to fruition (cf. 16:2)? This plan of theirs is a foolish one.
"So he went to his father and said, 'My father.' And he said, 'Here I am. Who are you, my son?' Jacob said to his father, 'I am Esau your firstborn; I have done just as you told me; please arise, sit and eat of my game, that your soul may bless me.' But Isaac said to his son, 'How is it that you have found it so quickly my son?' And he said, 'Because the LORD your God brought it to me.' Then Isaac said to Jacob, 'Please come near, that I may feel you, my son, whether you are really my son Esau or not.' So Jacob went near to Isaac his father, and he felt him and said, 'The voice is Jacob's voice, but the hands are the hands of Esau.' And he did not recognize him, because his hands were hairy like his brother Esau's hands; so he blessed him. Then he said, 'Are you really my son Esau?' He said, 'I am.' He said, 'Bring it near to me, and I will eat of my son's game, so that my soul may bless you.' So he brought it near to him, and he ate; and he brought him wine, and he drank" (Gen. 27:18-25).
Isaac's vision is gone, but even so he senses that this is not Esau. He knew the difference between Esau's voice and Jacob's. Nevertheless, Jacob lies to him three times here (twice regarding his identity and once regarding how he was able to bring the food so quickly) and is able to allay his father's doubts about his identity. The disguise helped tremendously in the deceptive plot and the whole scheme would have failed without Esau's clothes and animal skins. Isaac ate and drank and enjoyed a wonderful meal, no doubt.
"Then his father Isaac said to him, 'Come near now and kiss me, my son.' And he came near and kissed him; and he smelled the smell of his clothing, and blessed him and said: 'Surely, the smell of my son is like the smell of a field which the LORD has blessed. Therefore may God give you of the dew of heaven, of the fatness of the earth, and plenty of grain and wine. Let peoples serve you, and nations bow down to you. Be master over your brethren, and let your mother's sons bow down to you. Cursed be everyone who curses you, and blessed be those who bless you!'" (Gen. 27:26-29).
After the meal, the formal blessing is given. Interestingly, Isaac believes he is elevating Esau over Jacob, which is in direct contradiction to what God had foretold (cf. 25:23). Isaac was wrong to do this, and Jacob was wrong to pursue the blessing in this fashion. This entire affair would bring both of them problems. That being said, the words Isaac spoke turned out to be precisely true!