Before talking about Qur’an, at first people have to know the definition of the word “Miracle”. Miracle means the preternatural sign in which Allah “God” supports his Prophets and Messengers to challenge people and prove the righteous message.
The Holy Qur’an: is the miraculous word of Allah revealed in an Arabic tongue, which shows the Arabs good words and beautiful meanings that challenged them. Arabs were people of eloquence and poetry; so they wonder when they listened to some Qur’an which is more eloquent. It’s a miracle that continues to the Day of Resurrection for all generations and times… As soon as Walid Ibn al-Mughira {old honorable man in Quraysh who was died disbeliever} heard from the Prophet, peace be upon him until he said: “I heard from him a word not from the words of the jinn, nor from the words of mankind and I swear by God that it has sweetness and brilliance that it is fruitful above and lavished underneath, and nothing will be higher”.
Quran was and still full of inimitability, and it was a great challenge to the Arab society among Mohammed _peace be upon him_ which are known with eloquence and fluency.