Sayyiduna Abdullah bin Umar (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) entered the Ka'bah, and with him were Usamah bin Zayd and Bilal, and with them was also the keeper of the Ka'bah." Then when the Messenger of Allah (peace and blessings be upon him) came out, I was the first to enter, and I found Bilal (may Allah be pleased with him) at the door. I asked him: Where did the Messenger of Allah (peace and blessings be upon him) pray? He said: "Between the two front pillars."
Hadith Referenceالمعجم الكبير للطبراني / باب الباء / 1049