What must he who has committed adultery do to rid himself of the effects of his deed?

Fornication is among the gravest of prohibitions and the greatest of major sins. Allah has threatened polytheists, murderers, and fornicators with a compounded torment on the Day of Resurrection and eternal abode therein, disgraced, unless one repents, believes, and performs righteous deeds. Therefore, whoever has fallen into this sin must make sincere repentance by abandoning the sin, regretting it, and resolving never to return to it, out of fear of Allah, hope for His reward, and caution against His punishment. For Allah is Most Forgiving to whoever repents, believes, and performs righteous deeds.