Sheikh Salman al-Oadah
Prophet Muhammad (peace be upon him) taught his Companions the best supplication for beseeching Allah’s forgiveness. He taught them to say the following prayer every morning and evening:
“O Allah! You are my Lord. There is no God besides You. You created me, and I am your servant, and I honor Your covenant and Your promise as much as I can. I seek refuge with You from the evil that I do. I come to You by Your grace, and I come to You with my sins. So forgive me, for no one forgives sins but You.” [Sahīh al-Bukhārī (6307)]
This is most certainly the supplication of a believer, but of a believer who admits to stumbling into error; who says: “I honor Your covenant and Your promise as much as I can” and who appeals to the Lord with the words: “I seek refuge with You from the evil that I do. I come to You by Your grace, and I come to You with my sins.”
When we offer this supplication, we profess that our sins are all the more wrong in light of Allah’s blessings and grace that He showers upon us, but alas we have sinned and appeal to Allah in His infinite grace to forgive us.
This supplication is rich in meaning. There are so many ways in which it remedies the ills of the hearts of those who utter it.
Consider the words: “You created me, and I am your servant, and I honor Your covenant and Your promise as much as I can.” How honestly can we say these words? Even more, by uttering these worlds, we are reaffirming that our commitment to fulfill our covenant with our Lord to the best of our abilities. It is also a reminder to us of the covenant that we have with our Creator, which is mention in the following verse of the Qur’an:
“And when your Lord brought forth from the children of Adam, from their backs, their descendants, and made them bear witness against their own souls: Am I not your Lord? They said: ‘Yes! we bear witness.’ Lest you should say on the day of resurrection: ‘Surely we were heedless of this.’” [Sūrah al-A`rāf: 172]
We should appeal to Allah with this supplication for forgiveness whenever we commit a sin. We should also offer it every morning and evening, for if we do so, it will bring us a greater assurance that Allah in His grace will forgive us our mistakes and transgressions. It will also ensure that we cultivate our hearts to be penitent and humble.
Source : http://en.islamtoday.net/