The Koran is a book of myths, fables and fairy tales.
In other words Muhammad did not preach anything new. Everything he taught had been believed and practiced in Arabia long before he was ever born. Even the idea of "only one God" was borrowed from the Jews and the Christians.
The Koran says men were turned into apes because they broke the Sabbath. This was a popular legend in Muhammad's day (Suras 2:65; 7:163-166).
you will know the truth and the truth shall set you free !