Musannaf Ibn Abi Shayba 27:884

Shababa narrated to us, he said: Layth ibn Sa’d narrated to us, from Nafi’, from Ibrahim ibn Abdullah ibn Ma’bad, from Ibn Abbas, from Maymunah, she said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "A prayer in it—meaning the Mosque of Medina—is better than a thousand prayers in what is other than it, except for the Mosque of Mecca." Abu Bakr said: And the narrators of the people of Egypt do not include Ibn Abbas in it.