Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Praying in this mosque of mine is more virtuous than a thousand prayers in other mosques, except al-Masjid al-Haram; and one prayer in al-Masjid al-Haram is more virtuous than a hundred prayers in my mosque."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10278