Are the marriages contracted by non-Muslims valid?
Chapter on Marriage of Polytheists
Al-Mughni
Book of Marriage
Primary text
The marriages contracted by non-Muslims are valid. They are upheld when the non-Muslim parties embrace Islam or when they seek judgment from Muslim authorities, provided the woman is one with whom a marriage could be contracted initially. The specifics of their contract formation, such as the requirement for a guardian (wali), witnesses, or the specific form of offer and acceptance (ijab wa qabul), which are conditions for Muslim marriages, are not scrutinized. The consensus (ijma) among Muslims confirms this. Ibn Abd al-Barr stated that scholars are unanimous that if a couple embraces Islam simultaneously, they remain upon their existing marriage unless there exists a relationship of kinship or fosterage between them. Numerous individuals during the era of the Prophet, peace be upon him, embraced Islam along with their wives, and their marriages were upheld without the Prophet inquiring about the conditions or manner of their contract. This is an established fact known through continuous narration (tawatur) and necessity, thus reaching certainty.
Supporting text
The validity is upheld only if the woman is of a status permitting a new marriage contract at that moment. If she is one whose marriage cannot be initiated, such as a woman related through prohibited kinship or relationship, one currently observing an 'iddah (waiting period), an apostate, a pagan, a Zoroastrian, or a woman divorced three times, then the existing marriage is not upheld. However, if a man married a woman during her 'iddah and both embraced Islam only after the 'iddah concluded, their marriage is upheld because the initial contracting of marriage between them would have been permissible after the waiting period ended.