Isaac instantly realises that God has overruled. He has been deceived, and that was wrong, but God has allowed it to happen, and he has been overruled; he has been wrong all along, and he begins to shake with the realisation.
The writer to the Hebrews tells us that, ‘By faith Isaac blessed Jacob and Esau concerning things to come’ (Hebrews 11:20). This statement is all the more remarkable considering Isaac’s intention and how that intention was thwarted. An act can surely only be an act of faith if it is done knowingly and not if it is done in ignorance. A prayer can only be a prayer of faith if what is sought from God is what is received. But Isaac sought the blessing for Esau and received it for Jacob. How was this an act of faith? The answer is that when Isaac found out that he had been deceived, he did not try to change the blessing and give it to Esau instead. He gave this blessing in faith because it was not his blessing but the Lord’s and he knew it would be received. And then as it turned out in chapter 28:3-4 he did give a further blessing to Jacob when he dismissed him. ‘And God Almighty bless thee, and make thee fruitful, and multiply thee, that thou mayest be a multitude of people; And give thee the blessing of Abraham, to thee, and to thy seed with thee.’ So the Abrahamic blessing went fully to Jacob.