After Esau had given Jacob the rite as first born Isaac called Esau in not knowing about the exchange and asked him to go out hunting and cook the meat he gets and then he will give him the blessing as first born
when Isaac said this Esau actually wanted the blessing back so he tried to go behind Jacobs back and did it but in the other room Rebecca overheard this conversation and she helped Jacob because he was her favorite son.
Because Esau was such a hairy man Rebecca put goat skin on Jacob's neck and arms so it would trick Isaac because he couldn't see
when Esau came back he cooked the food and tried to get the blessing but when he went to Isaac, Isaac said that he had already gotten the blessing from him. Esau was aware of what Jacob did and became furious and started hunting Jacob and was trying to kill him
Rebecca heard that Esau started hunting Jacob so she warned Jacob and told him to run and never come back other wise Esau would kill him