What is the methodology used to keep the koran from the time it came down for the first time so far?

The methodology followed to preserve the Koran is receiving the Koran verbally and orally from man to man in a chain to the apostle of God (Blessing and peace be upon him). The one we should learn the Koran from must have received it verbally and orally and corrected it from an older man, and this man from an older man until they reach the messenger of God (Blessing and peace of God be upon him). So earlier Muslims laid a wise rule: "Don’t learn the Koran from Mos'hafey (someone See More▼ who learnt it from Mos'haf)" i.e. don’t learn the Koran from that who learnt it from mos'haf only not verbally from a sheikh, because such man will do mistakes in reciting. This is the right method old and contemporary Muslims follow in receiving and memorizing the Koran. They stipulate after good memorizing that one should get a license from earlier sheikhs.
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