Sahih Bukhari Volume 6, Book 65, Hadith 4496

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، قَالَ بَيْنَمَا النَّاسُ فِي صَلاَةِ الصُّبْحِ بِقُبَاءٍ إِذْ جَاءَهُمْ آتٍ فَقَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَدْ أُنْزِلَ عَلَيْهِ اللَّيْلَةَ، وَقَدْ أُمِرَ أَنْ يَسْتَقْبِلَ الْكَعْبَةَ، فَاسْتَقْبِلُوهَا‏.‏ وَكَانَتْ وُجُوهُهُمْ إِلَى الشَّأْمِ فَاسْتَدَارُوا إِلَى الْقِبْلَةِ‏.‏

Narrated By Ibn 'Umar : While some people were offering Fajr prayer at Quba mosque, someone came to them and said, "Qur'anic literature" has been revealed to Allah's Apostle tonight, and he has been ordered to face the Ka'ba (of Mecca) so you too, should turn your faces towards it. Their faces were then towards Sham (Jerusalem), so they turned towards the Qibla (i.e. Ka'ba of Mecca)."