Adam Clarke on Genesis 27:5

And Rebekah heard - And was determined, if possible, to frustrate the design of Isaac, and procure the blessing for her favorite son. Some pretend that she received a Divine inspiration to the purpose; but if she had she needed not to have recourse to deceit, to help forward the accomplishment. Isaac, on being informed, would have had too much piety not to prefer the will of his Maker to his own partiality for his eldest son; but Rebekah had nothing of the kind to plead, and therefore had recourse to the most exceptionable means to accomplish her ends.