Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with them both) said: I heard the Messenger of Allah (peace and blessings be upon him) saying: "One prayer in al-Masjid al-Haram is better than a thousand prayers in other mosques."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13902