Repentance is the giving up of sin and it is the best way of expressing regret for having committed a sinful act. It involves sincerely regretting a particular sin and then resolving never to perform it again. Repentance is the source of and way to success, and in the Quran we are told,
“Turn to Allah, O believers, that you may be successful.” (24:31)
No matter how grievous a person’s sin may be, God’s forgiveness is much greater. No one should be ashamed to turn toward God in repentance for one’s shortcomings, as God can erase the sins of whomever He pleases.
The Quran states,
“Say, O My servants who have transgressed against themselves, do not despair of the mercy of Allah; verily, Allah forgives all sins. Verily, He is the Forgiving, the Merciful.” (39:53)
Other verses which speak of God’s infinite mercy include the following,
“Tell My servants that I am the Forgiving, the Merciful” (15:49); “Will they not turn to Allah and ask His forgiveness? Allah is the Forgiving, the Merciful” (5:74); “Your Lord is full of forgiveness for mankind in spite of their wrongdoing.” (13:6)
Despite God’s ability to destroy mankind (if He so willed), God possesses the main characteristics of forgiveness and mercy. For this reason, Muslims begin nearly every action, speech, or endeavor with the words, “In the name of Allah, the Most Merciful, the Most Compassionate.”
Repentance is of benefit now and security for the Hereafter. Prophet Muhammad narrated that the act of repenting brings an increase in wealth, protection from danger, and an easing of hardships and difficulties. Furthermore, it has been said that the fastest way to attain closeness to God is to humble oneself before Him and to admit ones wrongdoing. The benefits of repentance for the next life are obvious – entrance into Paradise and safety from the Hellfire.
Repentance will be accepted up until the moment of death. Prophet Muhammad once said that if a person seeks repentance one year before dying, God will accept the repentance; even if a person seeks repentance one day before dying, God will accept it; the Prophet then pointed to his throat and said that even if someone seeks repentance before his soul reaches here (pointing to his throat), even then God will accept it!
Nonetheless, repentance should be done as soon as possible and should not be delayed for surely no one knows how or when one will die. This point has been emphasized again and again in the Islamic traditions and in one such anecdote, Imam Ali has said, “How numerous are the procrastinators who postpone [repenting and doing good deeds] until death overtakes them!”
Repentance should be done privately and secretly. People can establish a direct link to God while seeking repentance without the necessity of a third person interfering or even knowing about it. In fact, if a person commits a sin, he or she is not allowed to let others know about the sin! Prophet Muhammad once said to Imam Ali, “O Ali, blessed is one whom Allah looks upon while one is weeping for a sin that none is aware of except Allah.”
In addition to not revealing one’s own sins, every person must conceal the faults of his brother or sister to preserve that person’s honor and the honor of society. That person’s faults may be dealt with personally and privately, but it should not be spread among society.
God loves a person who sincerely repents for his or her sin; hence, the repented sin will be considered as if he or she had never committed that sin. Imam al-Baqir said, “He who repents of his sins is as one who has not any burden of sin.”
However, repentance must be sincere, and ultimately, it is only God who knows who is sincerely regretting his misdeeds and who is just speaking empty words.
A person came to Imam Ali and said, “I seek God’s forgiveness.” The Imam replied, “Do you know what asking God’s forgiveness is? Forgiveness is a word that stands on six supports. The first is to repent over the past. The second is to make a firm determination never to revert to it. The third is to discharge all the rights of people so that you may meet God quite clean with nothing which to account for. The fourth is to fulfill every obligation which you ignored in the past so that you may now be just with it. The fifth is to aim at the flesh grown as a result of unlawful earning so that you may melt it by grief of repentance till the skin touches the bone and a new flesh grows between them. And the sixth is to make the body taste the pain of obedience as you previously made it taste the sweetness of disobedience. On such an occasion, you may say, ‘I seek God’s forgiveness.’”
 Bismillahir Rahmanir Rahim.
 Ghurar al-Hikm, p.240.
 Bihar al-Anwar, v.77 p.63.
 Wasail al-Shia, v.16 p.74.
 Nahj al-Balagha (The Peak of Eloquence), sermon #426.