Musnad Ahmad 714:1

Aswad ibn Amir narrated to us, Shu'bah narrated to us, from Abu Aqil, the judge of Wasit, from Sabiq ibn Najiyah, from Abu Salam, who said: A man passed by in the mosque of Homs, and they said: "This is a servant of the Prophet, may Allah bless him and grant him peace." He said: So I stood up to him and said: "Narrate to me a hadith you heard from the Messenger of Allah, may Allah bless him and grant him peace, that is not circulated between you and him by other men." He said: The Messenger of Allah, may Allah bless him and grant him peace, said: "There is no Muslim servant who says, when he reaches the morning and when he reaches the evening, three times: 'I am pleased with Allah as a Lord, with Islam as a religion, and with Muhammad, may Allah bless him and grant him peace, as a Prophet,' except that it is a duty upon Allah to please him on the Day of Resurrection."