The Book of Pilgrimage (Kitab Al-Hajj)
Muslim :: Book 7 : Hadith 3209
Abu Huraira (Allah be pleased with him) narrated It directly from Allah's Apostle' (may peace be upon him) having said this: A prayer in my mosque is a thousand times more excellent than a prayer in any other mosque, except Masjid al-Haram (Mosque of the Ka'ba).