Abu al-Sha'tha' said that he heard Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) say: "The Prophet (peace and blessings be upon him) came walking between Usamah and Bilal (may Allah be pleased with them both) until they both entered the Ka'bah, and in it was a crosswise beam." Then when Bilal (may Allah be pleased with him) came out, I asked him what he (peace and blessings be upon him) had done. He said: "He (peace and blessings be upon him) left two-thirds of the beam to his right and prayed in the remaining third." (Abu al-Sha'tha' said:) I asked: How many rak'ahs did he pray? Ibn Umar (may Allah be pleased with them both) said: "I did not ask Bilal about that."
Hadith Referenceالمعجم الكبير للطبراني / باب الباء / 1025