Genesis 27:1-4; Genesis 27:22-23
It happened, that when Yitzchak was old, and his eyes were dim, so that he could not see, he called Esav his elder son, and said to him, "My son?" He said to him, "Here I am."
He said, "See now, I am old. I don't know the day of my death.
Now therefore, please take your weapons, your quiver and your bow, and go out to the field, and take me venison.
Make me savory food, such as I love, and bring it to me, that I may eat, and that my soul may bless you before I die.
Ya`akov went near to Yitzchak his father. He felt him, and said, "The voice is Ya`akov's voice, but the hands are the hands of Esav."
He didn't recognize him, because his hands were hairy, like his brother, Esav's hands. So he blessed him.