Musnad Ahmad 30:325

Abu Mu'awiyah, Waki', and Muhammad ibn 'Ubayd narrated to us, they said: Al-A'mash narrated to us, and Ibn Numayr narrated to us: Al-A'mash narrated to us, from Abu Salih, from Abu Hurayrah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "There is no newborn who is born except upon this religion." And Waki' said once: "Upon the religion."