Sahih Muslim Book 7, Hadith Number 3212.
Chapter : The merit of praying in the two mosques, at Mecca and Medina.
Yahya b. Sa’id (Allah be pleased with him) reported: I said to Abu Salih: Did you hear Abu Huraira (Allah be pleased with him) making a mention of the excellence of prayer in the mosque of Allah’s Messenger (may peace be upon him)? He said: No (I did not hear directly from Abu Huraira), but I heard Abdullah b. Ibrahim b. Qariz; say that’ he had heard from Abu Huraira (Allah be pleased with him) that Allah’s Messenger(may peace be upon him) had said: Prayer in this mosque of mine is better than a thousand prayers or is like one thousand prayers observed in other mosques besides It, except that it be in al-Masjid al-Haram. This Hadith has been narrated by Yahya b. Sa’id with the same chain of transmitters.