Jabir hin Yazid hin Al-Aswad [Al-Amir] narrated that his father said: "I attended Hajj with the Prophet. I prayed the Subh (Fajr) prayer with him in Masjid AI-Khaif." He said: "When the Prophet finished, he turned (from the Qiblah) and saw two men at the back of the people who had not prayed with him. He said, 'Bring them to me.' So I brought then while they were shuddering with fear. He said: 'What prevented you from praying with us?" They said: 'O Messenger of Allah!' We prayed at our camp.' So he said: 'Do not do that; when you pray in your camp then you come to a Masjid with a congregation, then pray with them. That will be a voluntary prayer for you.'"