The Sages elaborate on the events and conversation that took place between Isaac and Jacob, and the great fear that overcame Jacob at the moment his father sought to ascertain if he was indeed Esau.

Rabbi Yohanan said: At the moment that Jacob said in response to Isaac: “Because the Lord your God set it before me” (Genesis 27:20), Isaac said: This wording employing the name of God is not the wording used by Esau; rather, it is the wording used by Jacob, as it is stated: “The voice is the voice of Jacob” (27:22). Isaac first said to Jacob: “Please approach, and I will feel you” (27:21). Rabbi Yehoshua says: When Isaac said: “Please approach,” Jacob’s body trembled and he was stooped like melting wax. What did the Holy One, blessed be He, do? He told two angels, Gavriel and Mikhael, to help Jacob, and they assisted him; Mikhael to his right and Gavriel to his left. And He, may His name be blessed, in His glory, supported Jacob from behind him. God said to him: Jacob, why are you afraid and your body is stooped? I am God, and My host is in your assistance and supporting you, and you are afraid? Immediately, Isaac said to him: “The voice is the voice of Jacob, but the hands are the hands of Esau” (27:22). Your strength is greater than his. Concerning Esau, if he apprehends a person, that person is in his custody, but if that person flees, Esau is unable to do anything to him. But concerning you, even if a person flees from one end of the world to the other end, still: “The voice is the voice of Jacob”; you say words of prayer in the synagogue and he comes on his own. (Tanĥuma [Buber], Toledot)