Sahih Bukhari

Narrated Mujahid:Someone came to Ibn `Umar and said, ""Here is Allah's Messenger (ﷺ) entering the Ka`ba."" Ibn `Umar said, ""I went there but the Prophet (ﷺ) had come out of the Ka`ba and I found Bilal standing between its two doors. I asked Bilal, 'Did the Prophet (ﷺ) pray in the Ka`ba?' Bilal replied, 'Yes, he prayed two rak`at between the two pillars which are to your left on entering the Ka`ba. Then Allah's Messenger (ﷺ) came out and offered a two-rak`at prayer facing the Ka`ba