What is the purpose of the reserve requirement ?

The Federal Reserve's reserve requirement is 10%, which means that Bank XYZ must keep at least $40 million in an account at a Federal Reserve bank and may not use that cash for lending or any other purpose. The Federal Reserve is the central bank of the United States. It is a bank for banks.

https://investinganswers.com/financial-dictionary/economics/reserve-requirements-5131

answer; i believe its called ; checks   and balances;

the arab empire adopted the muslim religion as their main belief. arabs would influence the people from the territories they invaded towards islam (the muslim belief).

nevertheless, throughout the history of the arab empire, rulers brought intellectual individuals from other religions to their centers of learning. these other foreigners included jews, christians, greeks, persians, and indians.   these resulted in the adoption of important knowledge developed by these cultures by the arabic empire. for example, the works of aristotle were translated from greek to arab and indian scientists brought the numerical concept of "zero" to the arabs.

nowadays, 93% of the arab population is muslim, which at the same time is subdivided in sects including the sunni, zaini, alawi, shia. the remaining 7% is composed mainly of christians.