Surah 24. An-Nur, Ayah 9

Thus, the husband's accusation is to be regarded as proven if the wife refuses to take an oath to the contrary, and disproved if she solemnly sets her word against his. Inasmuch as this procedure, which is called li'an ("oath of condemnation"), leaves the question of guilt legally undecided, both parties are absolved of all the legal consequences otherwise attending upon adultery - resp. an unproven accusation of adultery - the only consequence being a mandatory divorce.

 This ruling is called li’ân in Islamic legal system. Once the husband and the wife swear each five times, as specified in 24:6-9, the marriage is terminated forever—which means that they can never be remarried.