These concepts, like others in Islamic law and jurisprudence, came from the "prescriptions, anecdotes, examples, and words of the Prophet, all gathered together and systematized by commentators according to an inductive, casuistic method." [1] Sometimes other sources such as al-urf, (the custom), al-'aql (reason) or al-ijma (consensus of the jurists) were employed.[2] In addition, Islamic law has developed areas of law that correspond to secular laws of contracts and torts.