Abu Dharr RA reported: I said: "Messenger of Allah (SAW): which mosque was setup first (on the earth?" He SAW said: "Al-Masjid al-Haram (the Sacred)." I (again) said: "Then which next?" He SAW said: "It was the Masjid Aqsa." I (again) said: "How long the space of time (between their setting up)? He (the Holy Prophet Muhammad SAW) said: "It was 40 years. And whenever the time for prayer, pray there, for that is a mosque," & in the hadith transmitted by Abu Kamil (the words are): "Whenever tine comes for prayer (solat), pray, for that is a mosque (for you)." - Sahih Muslim (No. 1056).