Reference: Fataawa az-Zawaaj wa ‘Ishratun-Nisaa. – Page 15, Fatwa No.116
Fataawa ash-Shaykh Muhammad Ibn al-‘Uthaymeen – Volume 2, Page 779
Question: A man committed adultery with a woman, so is it permissible for him to marry her before she makes towbah (seeks repentance) and what is required of her making towbah?
Is it carrying out the prescribed penalty or the towbah that is well known?
And if the towbah is to be carried out via the prescribed penalty, then we are in a country where such penalties are not carried out so what is the solution to this issue?
Response: An adultress is not to be married by her adulterer until they both make sincere towbah to Allaah in the manner that is well known. And it is imperative that he keeps away from her until the [marriage] contract with her, so as to find out if she is pregnant from the adultery or not. If it becomes clear that she is pregnant, then he is not to enter the [marriage] contract with her until she gives birth to the child. This is because the child [resulting] from adultery has no relation with the adultery, as the Prophet (sal-Allaahu ‘alayhi wa sallam) said:
«The child belongs to the owner of the bed (lil-firaash) and the adulterer gets the stone (i.e. nothing)».