From Sahih Muslim (Hadith 1178):
Ibn 'Umar reported:As the people were praying at Quba' a man came to them and said: It has been revealed to file Messenger of Allah (ﷺ) during the night and he has been directed to turn towards the Ka'ba. So turn towards it. Their faces were towards Syria and they turned round towards Ka'ba
Reference: Muslim 1178