Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) entered Masjid al-Haram on the day of the conquest of Makkah riding on the camel of Sayyiduna Usama bin Zaid (may Allah be pleased with them both). He made his camel sit in the courtyard of the noble Ka'bah, then ordered Uthman bin Talhah to bring the key. So he went to his mother to get the key, but his mother refused to give it. He said, "You must give me the key, otherwise the sword will pass through my back (I will be killed)." So she gave him the key. Then he opened the door of the noble House of Allah, and the Noble Prophet (peace and blessings be upon him) entered inside. Then he kept the door closed from inside for a while. Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates: I was a strong young man. People hurried towards the noble House of Allah, so I reached there before all of them. I found Sayyiduna Bilal (may Allah be pleased with him) standing at the door of the House of Allah. I asked, "O Bilal, where did the Messenger of Allah (peace and blessings be upon him) pray?" He replied, "Between the two front pillars." But I forgot to ask him how many units of prayer he performed. This narration is from Muhammad bin Amr.