The Blessing of the Firstborn

Esau has every right to be upset because he's been tricked by his brother. And even though he's the firstborn, his brother has received the blessing of the firstborn from his father Isaac through the deception that his mom came up with and that he played along with. He dressed himself up as his brother, made himself feel like his brother and smell like his brother - so he totally assumes the part of Esau. As a result of that, Isaac who was almost blind and couldn't tell that it was Jacob instead of Esau gave the blessing to Esau. Once the blessing is spoken, it cannot be taken away. There's no un-blessing of the first