Musnad Ahmad 714:2

Waki’ narrated to us, Mis’ar narrated to us, from Abu ‘Aqil, from Sabiq, from Abu Salam, from the servant of the Prophet, may Allah bless him and grant him peace, from the Prophet, may Allah bless him and grant him peace, that he said: "Whoever says: '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,' three times when he reaches the evening, and three times when he reaches the morning, it is incumbent upon Allah to please him on the Day of Resurrection."