What is the ruling when a husband claims the *mahr* (dower) is less than the customary *mahr al-mithl* (dower of the like) and the wife claims it is more?

Primary text

If the husband claims a dower less than the customary *mahr al-mithl*, and the wife claims a dower greater than it, the amount is reverted to the *mahr al-mithl*. The scholars of our school did not explicitly mention an oath (*yamin*). However, the preferred ruling is that both parties should engage in mutual imprecation (*tahaluf*). This is because what each party asserts is plausible, and deviation from this presumption requires an oath from the opposing party, similar to a denial in other claims. Moreover, since both parties share an equal lack of evidential clarity, mutual imprecation is prescribed, just as it is between disputing parties in a sale.