Mishkat al-Masabih #642

Ibn ‘Abbas said that when the Prophet entered the House (the Ka’ba) he made supplications in all sides of it, but did not perform salat till he had come out. When he came out he prayed two rak'as facing the Ka'ba and said, “This is the qibla.” Bukhari transmitted it and Muslim transmitted it from Ibn ‘Abbas from Usama b. Zaid.