I would treat as a prenuptial agreement and attempt enforcement as such. Was the agree signed in Texas? Do the parties have duel citizenship with another country? If is possible to take the agreement to another country and enforce it?
A pre-nup has certain requirement that must be met to be valid. I can't tell from what you submitted if they were done or not. But it certainly sounds like a valid Contract, and could be enforced in that matter. Talk with a good family law attorney to see what your options are.
Without limiting the potential for key information that would change the situation, I would say that it is likely the Haq Mehr would be enforceable in a Texas Family Court. However, before attempting to enforce the contract, there are probably other considerations to think about. If the marriage is to be judicially dissolved in Texas, the parties are due a just and right division of the community property. All property (income, real estate, personal property) is presumed community if acquired between the dates of marriage and divorce, except for inheritance and gift. Would an equitable division of the community property be more advantageous? If there are children, the parent who will be providing the primary home and care is owed child support with certain statutory guidelines setting out the amount of the support. Would enforcing the Haq Mehr cause one parent to be unable to pay adequate child support (which could be an equitable argument for not enforcing it). In addition, would the husband find it more palatable to honor the Haq Mehr than to fight over community assets and child support (if settling in this manner does not prejudice the parties)? If the parties agree to a specific settlement, the courts will often ratify that agreement - subject to the children's best interests being covered. There are many concerns to look at in order to determine whether the religious contract will be honored and is enforceable.
This response does not constitute legal advice. The facts and circumstances of any particular situation are unique and require an individual consultation before relying upon the general information contained here. The responding attorney welcomes the opportunity to consult with new clients to determine the appropriate direction and strategy for their case.