Musnad Ahmad 32:1160

Yazid narrated to us, Hammad ibn Salamah informed us, from Qatadah and Thabit, from Anas ibn Malik: "That the Messenger of Allah (peace and blessings of Allah be upon him), Abu Bakr, Umar, and Uthman used to begin the recitation with: {All praise is due to Allah, Lord of the worlds} [Al-Fatihah: 2]."