Sunan at-Tirmidhi (Jami-al-Tirmidhi), Chapter: Salah (Prayers)

that two men of Banu Khudrah and Banu Amr ibn Awf had an altercation on which mosque was built on taqwa. The man from Bana Khudrah said that the Prophet's mosque was built on taqwa, but the other said that it was the mosque at Quba. Both brought their alteraction to Allah's Messenger (SAW). He said, "It is this!" meaning, his own mosque, "and there is much good in it." [Ahmed 11046, Muslim 1398, Nisai 693]