The Quran is is the literal, absolute, eternal, perfect, and unadulterated word of God. Not a single word in the Quran has or ever will change.
When Our clear revelations are recited unto them, they who look not for the meeting with Us say: Bring a Lecture other than this, or change it. Say (O Muhammad): It is not for me to change it of my accord. Quran 10:15
Lo! We [Allah], even We, reveal the Reminder, and lo! We verily are its Guardian. 15:9
Recite that which hath been revealed unto thee of the Scripture of thy Lord. There is none who can change His words. 18:27
It is a glorious Qur'an. On a guarded tablet. 85:21-22
Well, except for when there is a problem that needs to be fixed. Then Allah adds another verse later to correct it.
Nothing of our revelation (even a single verse) do we abrogate or cause be forgotten, but we bring (in place) one better or the like thereof. 2:106
And when We put a revelation in place of (another) revelation, - and Allah knoweth best what He revealeth - they say: Lo! thou art but inventing. 16:101
The Quran explains everything about everything.
We reveal the Scripture unto thee as an exposition of all things. 16:89
It is a scripture that was revealed by Allah to Muhammad.
(This is) a Scripture which We have revealed unto thee (Muhammad). 14:1
It is true beyond the slightest doubt.
