From Sahih Bukhari (Hadith 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
Reference: Bukhari 4488