Sahih al-Bukhari 4488
Narrated Ibn `Umar:
While some people were offering Fajr prayer in the Quba' mosque, some-one came and said, "Allah 
has revealed to the Prophet (ﷺ) Qur'anic instructions that you should face the Ka`ba (while praying) so 
you too, should face it." Those people then turned towards the Ka`ba.
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ سُفْيَانَ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ بَيْنَا النَّاسُ يُصَلُّونَ الصُّبْحَ فِي مَسْجِدِ قُبَاءٍ إِذْ جَاءَ جَاءٍ فَقَالَ أَنْزَلَ اللَّهُ عَلَى النَّبِيِّ صلى الله عليه وسلم قُرْآنًا أَنْ يَسْتَقْبِلَ الْكَعْبَةَ فَاسْتَقْبِلُوهَا‏.‏ فَتَوَجَّهُوا إِلَى الْكَعْبَةِ‏.‏