" O Allah You are my Cherisher.There is no deity except You. You have created me and I am Your servant and as far as possible, I abide by my solemn promise and covenant(which I made to You). I seek Your protection against the consequences of my wrong doings. I full acknowledge the grace You have bestowed upon me and I confess my faults.So pardon me as none besides You can pardon sins."
Rasulullah(sallallahu alaiyhi wassallam) said that any servant of Allah who recites the above Istighfaar with sincerity and conviction of heart at any time during the day and dies before nightfall, will most certainly enter Jannah. Similarly,one who recites it at night and dies before morning will enter Jannah." (BUKHARI)
It is for this reason that it has been named "Sayyidul- Istighfaar" meaning "The leading form of Repentance."
Also, the extraordinary merit of this Istighfaar lies most probably in the abundance of humility and servitude found in this Duaa.