Musnad Ahmad 1017:79

Abu Kamil narrated to us, Zuhayr narrated to us, al-Walid ibn Tha'labah al-Ta'i narrated to us, from Ibn Buraydah, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever says when he reaches the morning or when he reaches the evening: 'O Allah, You are my Lord, there is no god but You. You created me and I am Your servant, and I am upon Your covenant and Your promise as much as I am able. I seek refuge in You from the evil of what I have done. I acknowledge Your favor upon me, and I acknowledge my sin, so forgive me; for indeed, no one forgives sins except You.' Then he dies on that day or in that night, he will enter Paradise."