Sahih Bukhari Volume 6, Book 65, Hadith 4495

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ مُسْلِمٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دِينَارٍ، قَالَ سَمِعْتُ ابْنَ عُمَرَ ـ رضى الله عنهما ـ يَقُولُ بَيْنَا النَّاسُ فِي الصُّبْحِ بِقُبَاءٍ إِذْ جَاءَهُمْ رَجُلٌ فَقَالَ أُنْزِلَ اللَّيْلَةَ قُرْآنٌ، فَأُمِرَ أَنْ يَسْتَقْبِلَ الْكَعْبَةَ، فَاسْتَقْبِلُوهَا‏.‏ وَاسْتَدَارُوا كَهَيْئَتِهِمْ، فَتَوَجَّهُوا إِلَى الْكَعْبَةِ وَكَانَ وَجْهُ النَّاسِ إِلَى الشَّأْمِ‏.‏

Narrated By Ibn Umar : While some people were at Quba (offering) morning prayer, a man came to them and said, "Last night Qur'anic Verses have been revealed whereby the Prophet has been ordered to face the Ka'ba (at Mecca), so you too should face it." So they, keeping their postures, turned towards the Ka'ba. Formerly the people were facing Sham (Jerusalem)