What is the ruling on a marriage contract made by a sick husband who settles a dowry exceeding the customary *mahr* (Mahr al-Mithl)?

Primary text

If a husband contracts marriage during his illness, setting the dowry (*sadaq*) at ten units when his customary dowry (*sadaq mithlihi*) is five, and he only possesses the ten, the favoritism (*muhabah*) in the excess dowry (the extra five units) is voided if his heirs contest it, unless all heirs consent to ratify it. If the wife does not inherit from him due to religious differences or other reasons, she receives her customary dowry (five units) and one-third of the amount he favored her with (one-third of the excess five units).