• They may, however, be regarded as individual obligations (fardu ‘ayn) when the obligation to perform such tasks is required by the leadership, when someone is the only available skilled or specialized professional for the service, or when, as in emergencies, an essential service has to be carried out but those responsible are unable or unavailable to perform their tasks. (al-sumaih, The Sunni Concept of Jihad in Classical Fiqh and Modern Islamic Thought)