Musannaf Ibn Abi Shayba 3:5398

Ibn ‘Ulayyah narrated to us, from al-Jurayri, from al-Hakam ibn al-A’raj, who said: I asked Muhammad about the Duha prayer while he was leaning his back against the chamber of the Prophet, may Allah bless him and grant him peace. He said: "It is an innovation, and what an excellent innovation it is."