An Isaac that is now old and is nearly blind tells his oldest son Esau to prepare him a plate of food the way he likes it and he will give Esau his blessing.
While Esau goes out hunting for meat for his fathers plate, Rebekah tells Isaac her plan.
Go now to the flock and bring me two choice young goats from there, that I may prepare them as a savory dish for your father, such as he loves. Then you shall bring it to your father, that he may eat, so that he may bless you before his death.” Genesis 27 9-10
After preparing his father's dish Jacob goes to Isaacand tells him that he is Esau, Jacob wore goat skins so that when Isaac felthis arms they would feel hairy like Esau's. Because of Isaacs bad eyesight andJacob wearing Esau's clothes Isaac thinks Jacob is Esau and gives him his blessing.
It is I, your first born, Esau
After Jacob receives the blessing he leaves and Esau enters, Esau says “Let my father arise and eat of his son’s game,that you may bless me.” Isaac responds with the fact that he already gave his blessing to Esau.
After Isaac informs Esau that he already gave the blessing, Esau is furious, he demands the blessing and his birthright but Isaac is upset and conflicted because he already gave it to someone who he thought was Esau.
Esau pledges that he will kill Isaac for what he has done. Rebekah hears of this and sends her son to Haran where her brother Laban lives. She tells him to live there until his brothers rage subsides and then they will send for him.