Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad

Zina (fornication) is an enormous sin. Fornicators need to repent sincerely to Allah and to earnestly ask for forgiveness resolving to start a new period of chastity and purity. They need also to increase their good deeds to wipe out bad ones. After mentioning a number of grave sins and the punishment that awaits those who commit them, Allah Almighty said what means, “Except for whoever repents, and believes, and does righteous deeds. For [the likes of] them, then, God will substitute their misdeeds with good deeds. And ever is God all-forgiving, mercy-giving.” (Al-Furqan 25:70)

As for their marriage, Allah Almighty says what means “A man who fornicates shall not marry anyone but a woman who fornicates or an idolatress. And [as for] the woman who fornicates, none shall marry her but a fornicator or an idolater- and such [marriage] is forbidden for the believers.” (An-Nur 24:3)

There are different interpretations for this verse and therefore scholars have differed over the validity of such marriage.  However, there is no disagreement among scholars over the validity of their marriage if both fornicators repent sincerely to Allah Almighty. Repentance wipes away sins and leaves a person as if born anew. But if they do not repent, the validity of their marriage will be controversial.

Almighty Allah knows best.