Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1071
Al-Bara' b. 'Azib reported: I said prayer with the Apostle (may peace be upon him) turning towards Bait-ul-Maqdis for sixteen months till this verse of Surah Baqara wis revealed:" And wherever you are turn your faces towards it" (ii. 144). This verse was revealed when the Apostle (may peace be upon him) had said prayer. A person amongst his people passed by the people of Ansar as they were engaged in prayer. He narrated to them (this command of Allah) and they turned their faces towards the Ka'ba.