An-Nisa 4:16

Wallathani ya/tiyanihaminkum faathoohuma fa-in taba waaslahafaaAAridoo AAanhuma inna Allaha kanatawwaban raheema

And the two who commit it [i.e., unlawful sexual intercourse] among you - punish [i.e., dishonor] them both. But if they repent and correct themselves, leave them alone. Indeed, Allāh is ever Accepting of Repentance and Merciful.

Those two of you who commit it, chastise both of them. However, if they repent and make amends, then, overlook them. Surely, Allah is Most-Relenting, Very-Merciful.