If the husband and wife differ in any one of these five areas, compatibility is considered lacking. The absence of compatibility, however, does not affect the validity of the marriage itself, for compatibility is not a condition of validity. The Prophet ﷺ instructed Fāṭimah bint Qays to marry Usāmah ibn Zayd, and she did so at his command—this report is agreed upon. Compatibility is therefore only a condition for the marriage to become binding. Hence, if a woman is married to someone who is not her equal, any party that objects—whether the woman herself or her guardians—may petition to have the marriage annulled. A man once married his daughter to his nephew in order to raise the latter’s social standing, and the Prophet ﷺ granted the daughter the option (to accept or refuse). Some scholars maintain that compatibility is a prerequisite for the marriage’s validity; this is one narration transmitted from Aḥmad.

Shaykh Taqī al-Dīn said: “What Aḥmad’s words imply is that, once it becomes clear a man is not a suitable match, the couple must be separated. The guardian has no right to marry the woman to someone who is not her equal, nor does the prospective husband or even the woman herself have the right to proceed. Compatibility is not like financial matters such as the woman’s dower: if she and her guardians wish, they may demand it, and if they wish, they may waive it. Rather, compatibility is an issue that they must take into consideration.” End quote.