It is narrated from Sayyiduna Shaddad bin Aws (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Any servant who says in the morning and in the evening: 'O Allah, You are my Lord, there is none worthy of worship except You. You created me and I am Your servant, and I abide by Your covenant and promise as far as I am able. I acknowledge Your blessing upon me, and I also acknowledge my sin, so forgive my sins, for indeed none forgives them except You', then if he dies that day he will enter Paradise, and if he dies that night he will enter Paradise."
Hadith Referenceالمعجم الكبير للطبراني / باب الشين / 7154