Working for a company that transports documents and parcels is permissible, but if the company specialises in transporting unlawful things, such as delivering documents for Riba-based banks, or transporting alcohol, movies or music, then working for it becomes unlawful.

1. Lawful work should be in a permissible field and should not involve helping others to commit unlawful acts such as working in buying and selling, and rental of permissible things such as selling food, medicine, tools and equipment, and the like. It also includes working in teaching, medicine, engineering, electricity, carpentry, and manufacturing, and innumerable other permissible types of work. 2. Prohibited work includes working in Riba-based banks or commercial insurance companies, or carrying alcohol, or raising pigs, or writing down contracts of Riba, or equipping places for gambling, or selling things that it is thought most likely will be used for unlawful purposes, such as selling weapons to bandits, and other things that are regarded as prohibited and sinful, or helping in it directly or almost directly.

1- Some jobs are haram in and of themselves such as working in riba-based banks and places where alcohol is sold. 2- Some jobs may be haram because of things in the work-place that are contrary to Shari`ah such as mixing between men and women, or because it is stipulated that one should wear haram clothing or do other things that are contrary to Shari`ah such as shaving the beard. It is not permissible for the Muslim to do either type of job. However, there are guidelines to be followed and some exceptions in cases of need and when certain evils are unavoidable.

If the doctor has started to pray, then he is told of an emergency case and there is no one available to take care of it except him, then he must interrupt his prayer and treat the patient.