Sayyiduna Abu Umamah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever says three times in the morning: O Allah, to You belongs all praise; there is no true god but You; You are my Lord and I am Your servant; I have believed in You, making my religion sincerely Yours; I have entered the morning upon Your covenant and Your promise as far as I am able; I turn to You in repentance from my evil deeds, and I seek Your forgiveness for my sins which none forgives but You, then if he dies on that day, he enters Paradise. And if he says three times in the evening: O Allah, to You belongs all praise; there is no true god but You; You are my Lord and I am Your servant; I have believed in You, making my religion sincerely Yours; I have entered the evening upon Your covenant and Your promise as far as I am able; I turn to You in repentance from my evil deeds, and I seek Your forgiveness for my sins which none forgives but You" then whoever dies that night enters Paradise. The narrator said: Then the Messenger of Allah (peace and blessings be upon him) would swear an oath such as he did not swear about anything else, saying: "By Allah, no servant says it three times in the morning and then dies on that day except that he will certainly enter Paradise, and if he says it three times in the evening and then dies that night, he will certainly enter Paradise."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7771