Musnad Ahmad 32:1031

Isma'il narrated to us, he said: Sa'id ibn Yazid informed us, he said: I said to Anas ibn Malik: "Did the Messenger of Allah, may Allah bless him and grant him peace, begin the recitation with 'In the name of Allah, the Most Gracious, the Most Merciful' or with 'All praise is due to Allah, Lord of the worlds'?" He said: "You are asking me about something that no one has asked me about before."