Sahih al-Bukhari 4490
Narrated Ibn `Umar:
While some people were offering morning prayer at Quba' a man came to them and said, "A Qur'anic 
Order has been revealed to Allah's Messenger (ﷺ) tonight that he should face the Ka`ba at Mecca (in prayer), 
so you too should turn your faces towards it." At that moment their faces were towards Sham (i.e. 
Jerusalem) (and on hearing that) they turned towards the Ka`ba (at Mecca).
حَدَّثَنَا خَالِدُ بْنُ مَخْلَدٍ، حَدَّثَنَا سُلَيْمَانُ، حَدَّثَنِي عَبْدُ اللَّهِ بْنُ دِينَارٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ بَيْنَمَا النَّاسُ فِي الصُّبْحِ بِقُبَاءٍ جَاءَهُمْ رَجُلٌ فَقَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَدْ أُنْزِلَ عَلَيْهِ اللَّيْلَةَ قُرْآنٌ، وَأُمِرَ أَنْ يَسْتَقْبِلَ الْكَعْبَةَ أَلاَ فَاسْتَقْبِلُوهَا‏.‏ وَكَانَ وَجْهُ النَّاسِ إِلَى الشَّأْمِ فَاسْتَدَارُوا بِوُجُوهِهِمْ إِلَى الْكَعْبَةِ‏.‏