Sahih Bukhari Volume 9, Book 91, Hadith Number 358.

Narrated By Al-Bara’ : When Allah’s Apostle arrived at Medina, he prayed facing Jerusalem for sixteen or seventeen months but he wished that he would be ordered to face the Ka’ba. So Allah revealed:

‘Verily! We have seen the turning of your face towards the heaven; surely we shall turn you to a prayer direction (Qibla) that shall please you.’ (2.144) Thus he was directed towards the Ka’ba. A man prayed the ‘Asr prayer with the Prophet and then went out, and passing by some people from the Ansar, he said, “I testify. that I have prayed with the Prophet and he (the Prophet) has prayed facing the Ka’ba.” Thereupon they, who were bowing in the ‘Asr prayer, turned towards the Ka’ba.