The Holy Qur’an is the greatest of all books and it being the Word of Allah the Exalted and revealed from Him is enough to be a proof to be the greatest.
“And indeed, the Qur’an is the revelation of the Lord of the worlds. The Trustworthy Spirit has brought it down. Upon your heart, [O Muhammad] – that you may be of the warners – In a clear Arabic language. And indeed, it is [mentioned] in the scriptures of former peoples.” (26:192-196)
“Blessed is He who sent down the Criterion upon His Servant that he may be to the worlds a warner -” (25:1)
“Then I swear by the setting of the stars, And indeed, it is an oath – if you could know – [most] great. Indeed, it is a noble Qur’an. In a Register well-protected; None touch it except the purified. [It is] a revelation from the Lord of the worlds.” (56:75-80)
At one place; Allah the Exalted mentions Qur’an “الكتاب المبين” and at another “الكتاب الحكيم” and at another “تنزيل الكتاب من الله العزيزالحكيم”.
And at some places Allah the Exalted takes an oath while mentioning it
“حم ~ و الكتاب المبين ~ انا انزلناه قرآناً عربياً لعلكم تعقلون” at another place
“يس ~ والقران الحكيم” also “ص ~ والقران ذي الذكر”.
Henceforth not needing but still Allah the Exalted educating the Human creation about different attributes of the Qur’an and taking oath to manifest its Greatness in order to make people understand its importance and to make them revere it from the bottom of their hearts and to make it as a guiding principle in their lives.