Musannaf Ibn Abi Shayba 3:5147

Sufyan ibn 'Uyaynah narrated to us, from Abu al-Zinad, from Kharijah ibn Zayd, that the Prophet (may Allah bless him and grant him peace) said: "The mosque which was founded on piety from the first day is the mosque of the Prophet (may Allah bless him and grant him peace)."