Ubadah ibn Al-Samit reports: "God's messenger said to us: 'Pledge to me that you will associate nothing as a partner with God, and that you shall not steal, commit adultery, kill your children, lie about who fathers your children, or disobey in anything reasonable. Anyone of you who remains true to his pledge shall have his reward from God. The one who commits any of these in private and God grants him secrecy will remain subject to God's decision in his case: He may forgive him and He may punish him.' We gave him our pledges in these terms."
Ubadah, the reporter of this hadith, was one of 12 men from among the very early Muslims from Madinah who came to meet the Prophet (pbuh) in Makkah during the pilgrimage season and assure him of their loyalty to him. They wanted to advocate Islam among their people and to ensure that Islam would have a solid base in Madinah. The Prophet met them at a place called Aqabah in Mina, where all pilgrims stay for two or three days.
The meeting took place at night so that the unbelievers who continued to hold power in Makkah would not be able to frustrate their purpose. This pledge was a first step toward the establishment of the first Muslim state in history. A year later, 73 men and two women from Madinah met the Prophet in the same place where a new pledge was given and agreement that all the Muslims of Makkah would be joining their brethren in Madinah was made.
The terms of this pledge are very clear. Some of the sinful actions the pledge outlines, such as stealing and adultery, carry a mandatory punishment when they are proven or a confession is made. Others have a discretionary punishment determined by a Muslim judge in accordance with legal provisions and the circumstances of the case.
What the Prophet states in this hadith is that when punishment is administered in this life, this puts an end to the case. No further punishment is inflicted by God on the perpetrator, either in this life or in the life to come.
Should a sinful action, or a crime, be committed and the perpetrator escape punishment then the case is left to God to decide in His wisdom, on the Day of Judgment. He may punish the perpetrator or pardon him. This principle applies to all Muslims and all actions that Islam forbids. The correlation of this principle is that we are all encouraged to repent of any sin and offence we may commit.
Repentance means a genuine regret and a determination not to indulge in such an action again. Such repentance earns forgiveness from God. Hence the Prophet makes clear that any offence that remains unpunished in this life is left to God to decide. Only God can judge whether repentance is genuine or not. An offender may assure us that he has repented, but only God can tell whether this is true.
Two points need to be made clear: The first is that Islam encourages genuine repentance. It acknowledges that any one may yield to temptation and commit a sin. God will forgive any sinner who regrets his action and resolves not to repeat it. Islam prefers this to confessing the crime and seeking to be punished for it. Repentance is a much better way of encouraging good behaviour.
The second point is that God forgives all sins except those that represent aggression against other people. If someone steals or spreads false rumours about another, and then genuinely repents, God forgives him the part that is owed to Him, which is the violation of God's law. What is owed to the other person is not forgiven until God brings the two people concerned and asks the victim whether he is willing to forgive the offender.
If such forgiveness is granted, God will reward that person for his kindness. If it is not, then God will punish the offender or He, in His grace, will take over the matter and ensure that the victim is amply compensated.