On the authority of Shaddad ibn Aws, may Allah be pleased with him, the Prophet, Sallallahu Alayhi Wa Aalihi Wa Sallam, said, “The chief of prayers for forgiveness is:
Allahumma anta rabbee la ilaha illa anta, khalaqtanee wa-ana ‘abduka, wa-ana ‘alaa ‘ahdika wawa’dika mas-tata’tu, a’oothu bika min sharri ma sana’tu, aboo-o laka bini’matika ‘alaya, wa-aboo-o bizambee, faghfir lee zunoobi fa-innahu la yaghfiruz-zunooba illa ant.
‘O Allah, You are my Lord, none has the right to be worshiped except You, You created me and I am Your servant and I abide to Your covenant and promise [to honor it] as best I can, I take refuge in You from the evil of which I committed. I acknowledge Your favor upon me and I acknowledge my sin, so forgive me, for verily none can forgive sins except You.’
The Prophet, Sallallahu Alayhi Wa Aalihi Wa Sallam, added, “If somebody recites it during the day with firm faith in it and dies on the same day before the evening, he will be from the people of Paradise and if somebody recites it at night with firm faith in it and dies before the morning he will be from the people of Paradise.”