Parshah Toldot

Isaac was forty years old when he took Rebecca to wife (Genesis 25:20)

For three years, from the Binding of Isaac at age 37 to his marriage at age 40, Isaac was in the Garden of Eden.

(Asarah Maamarot)

The voice is the voice of Jacob, but the hands are the hands of Esau (27:22)

"The voice is the voice of Jacob" -- no prayer is effective unless the descendants of Jacob have a part in it. "The hands are the hands of Esau" -- no war is successful unless the descendants of Esau have a part in it.

(The Talmud)