Musnad Ahmad 941:67

'Abd al-Razzaq narrated to us, Ibn Jurayj and Rawh informed us, they said: Ibn Jurayj narrated to us, he said: I said to 'Ata': Did you hear Ibn 'Abbas say: "You were only commanded to perform Tawaf, and you were not commanded to enter [the Ka'bah]?" He said: He did not use to forbid entering it, but I heard him say: Usamah ibn Zayd informed me: "That when the Prophet, peace and blessings of Allah be upon him, entered the House, he supplicated in all of its corners, and he did not pray inside it until he exited. When he exited, he performed two rak'ahs facing the Ka'bah." 'Abd al-Razzaq said, and he said: "This is the Qiblah."