The Noble Qur’aan is inimitable in its words and rhetoric: And if you (Arab pagans, Jews, and Christians) are in doubt concerning that which We have sent down (i.e. the Qur’aan) to Our slave (Muhammad صلى الله عليه وسلم), then produce a Soorah (chapter) of the like thereof and call your witnesses (supporters and helpers) besides Allaah, if you are truthful.
It is inimitable in the easiness of its understanding and recitation: And We have indeed made the Qur’aan easy to understand and remember; then is there anyonee who will remember (or receive admonition)?
It is inimitable in the narratives of past nations it relates to derive lessons: We relate unto you (Muhammad صلى الله عليه و سلم) the best of stories through Our Revelations unto you, of this Qur’aan. And before this (i.e. before the coming of Divine Revelation to you), you were among those who knew nothing about it (the Qur’aan). Allaah (Glorified be He) also says:Indeed in their stories, there is a lesson for men of understanding. It (the Qur’aan) is not a forged statement but a confirmation of (Allaah’s existing Books) which were before it [i.e. the Tawraat (Torah), the Injeel (Gospel) and other Scriptures of Allaah] and a detailed explanation of everything and a guide and a Mercy for the people who believe.… read more here.