Abdullah (may Allah be pleased with them both) said: On the day of the Conquest, the Prophet (peace and blessings be upon him) came from the upper part of Makkah on his she-camel, with Usamah bin Zayd (may Allah be pleased with him) riding behind him. With him (peace and blessings be upon him) was Bilal (may Allah be pleased with him), and also Uthman bin Talhah (may Allah be pleased with him), one of the custodians of the House, until he made the camel kneel in the mosque and told him to bring the key of the House. He opened it, and the Messenger of Allah (peace and blessings be upon him), Usamah, Bilal and Uthman (may Allah be pleased with them) entered and stayed inside for a long part of the day. Then he came out, and the people rushed forward. Abdullah bin Umar (may Allah be pleased with them both) was the first to enter, and he found Bilal (may Allah be pleased with him) standing behind the door. He asked him: Where did the Prophet (peace and blessings be upon him) pray? He pointed to the place where he had prayed. Abdullah said: I forgot to ask him how many rak'ahs he prayed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9721