Narrated Ibn `Umar:While some people were offering Fajr prayer at Quba' (mosque), some-one came to them and said, "Tonight some Qur'anic Verses have been revealed to the Prophet (ﷺ) and he has been ordered to face the Ka`ba (at Mecca) (during prayers), so you too should turn your faces towards it." At that time their faces were towards Sham (Jerusalem) so they turned towards the Ka`ba (at Mecca).
حَدَّثَنَا يَحْيَى بْنُ قَزَعَةَ، حَدَّثَنَا مَالِكٌ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، قَالَ بَيْنَا النَّاسُ بِقُبَاءٍ فِي صَلاَةِ الصُّبْحِ إِذْ جَاءَهُمْ آتٍ فَقَالَ إِنَّ النَّبِيَّ صلى الله عليه وسلم قَدْ أُنْزِلَ عَلَيْهِ اللَّيْلَةَ قُرْآنٌ، وَقَدْ أُمِرَ أَنْ يَسْتَقْبِلَ الْكَعْبَةَ فَاسْتَقْبِلُوهَا. وَكَانَتْ وُجُوهُهُمْ إِلَى الشَّأْمِ فَاسْتَدَارُوا إِلَى الْكَعْبَةِ.
Bukhari
Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) • Hadith 18