Sayyiduna Ubadah bin Samit (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) led us in the Fajr prayer, and recitation became difficult for him. When he finished the prayer, he said: "It seems to me that you recite behind your Imam." We said: "Yes, O Messenger of Allah! We recite quickly." He said: "Do not recite anything except Umm al-Qur'an (Surah al-Fatihah), for whoever does not recite it, his prayer is not valid."