Musnad Ahmad 32:1182

Mu'adh narrated to us, Sa'id ibn Abi 'Arubah narrated to us, from Qatadah, from Anas, "That the Prophet, peace and blessings of Allah be upon him, and Abu Bakr, and 'Umar, and 'Uthman used to begin their recitation in their prayer with: {All praise is due to Allah, Lord of the worlds} [Al-Fatihah: 2]."