I prayed behind the Prophet ﷺ, Abu Bakr and Umar, and they would all begin with "al-Hamdu lillah" [Fatihah 1:2].
حدثنا سفيان عن أبي أيوب عن قتادة
صليت خلف النبي ﷺ وأبي بكر وعمر فكانوا يفتتحون ب {الحمد}
Its isnad is sahih. It came earlier at 11930, and in the printed edition it reads Abu Ayub, which is an error, for Imam Ahmad relates all the narrations as, Sufyan from Ayub.