Narrated 'Abdullah bin 'Umar:

While the people were at Quba offering the morning prayer, suddenly a person came to them saying, "Tonight Divine Inspiration has been revealed to Allah's Apostle and he has been ordered to face the Ka'ba (in prayers): therefore you people should face it." There faces were towards Sham, so they turned their faces towards the Ka'ba (at Mecca).

حَدَّثَنَا إِسْمَاعِيلُ، حَدَّثَنِي مَالِكٌ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ بَيْنَا النَّاسُ بِقُبَاءٍ فِي صَلاَةِ الصُّبْحِ إِذْ جَاءَهُمْ آتٍ فَقَالَ إِنَّ رَسُولَ اللَّهِ ﷺ قَدْ أُنْزِلَ عَلَيْهِ اللَّيْلَةَ قُرْآنٌ، وَقَدْ أُمِرَ أَنْ يَسْتَقْبِلَ الْكَعْبَةَ فَاسْتَقْبِلُوهَا. وَكَانَتْ وُجُوهُهُمْ إِلَى الشَّأْمِ فَاسْتَدَارُوا إِلَى الْكَعْبَةِ.