A married man committed adultery with a married woman in a country that does not implement the [Islamic] prescribed legal punishment for this crime. How is he to repent? To do so, must the prescribed punishment be inflicted upon him?

Abu Hurayra, may Allah be pleased with him, said: "I heard the prophet [pbuh] say, "All members of my community are pardoned except for those who announce their sins.
Among those who announce their sins is someone who commits a crime by night; Allah has concealed it, yet when morning comes he says: "O, so-and-so! Yesterday I did such-and-such." He spent the night with his sins covered by his Lord, and when he wakes up he exposes what Allah has concealed" [Bukhari and Muslim].

A person who commits a sin must refrain from divulging it when Allah has concealed it from others; one of the attributes of Allah Almighty is concealing human faults and failings. A person who announces his sins when Allah has concealed them attaches little importance to His protection and is ungrateful to His grace and mercy. Repentance is by doing the following:
- desisting from one's sin;
- regretting having done it;
- resolving never to commit it again;
- asking for Allah's forgiveness in abundance.

Allah almighty does not require that a person who has committed a sin for which there is a prescribed legal punishment to strive to have the punishment inflicted upon him.
Rather, he is commanded to conceal his mistake; the ruler is the one to exact punishments as it is one of his duties.

It has been reported that a man, Ma'iz ibn Malik, fornicated with a slave girl who was not permissible for him. Huzal ordered him to go to the prophet [pbuh] before whom Ma'iz testified against himself four times. After ordering that he be stoned to death, the prophet [pbuh] turned to Huzal and said: "It would have been better if you had covered him with your cloak" [Abu Dawud and al-Nisa`i].