Musnad Ahmad 31:845

Musa ibn Dawud narrated to us, Layth narrated to us, from ‘Imran ibn Abi Anas, from Sa‘id ibn Abi Sa‘id al-Khudri. And Qutayba narrated it to us, and ‘Imran ibn Abi Anas said, from Ibn Abi Sa‘id, from Abu Sa‘id al-Khudri, who said: Two men disputed regarding the mosque which was founded upon righteousness. One of them said: "It is the Mosque of Quba." The other said: "It is the Mosque of the Prophet, may Allah bless him and grant him peace." The Prophet, may Allah bless him and grant him peace, said: "It is this mosque of mine."