It is reported from Sayyiduna Ibn Umar (may Allah be pleased with them both) that when he began the prayer, he would say the takbir, then recite: "In the name of Allah, the Most Gracious, the Most Merciful. All praise is for Allah, Lord of the worlds" [Surah al-Fatihah: 1-2], and when he had finished Surah al-Fatihah, he recited "In the name of Allah, the Most Gracious, the Most Merciful" [Surah al-Fatihah: 1]. Nafi' said that Ibn Umar (may Allah be pleased with them both) used to say: If it is not to be recited, then why was it written in the Qur'an?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2382