Pak

Like the blessing of Joseph's two sons, the blessing of Jocob was not the handy work of Issac, God had already chosen Jocob. What Issac did was just a formality... This made it impossible for Isaac to reverse the blessings... Isaac was just a tool for God to bless Jacob. God on the other had made sure that his promises come to pass, for He is a covenant keeping God and He is not a man that should lie...so He just made sure His promises are fulfill.