"Verily, We, it is We Who have sent down the Dhikr (i.e. the Quran) and surely, We will guard it (from corruption)"
[Al-Hijr 15:9]

"And indeed, We have made the Quran easy to understand and remember, then is there any that will remember (or receive admonition)?"
[Al-Qamar 54:40]

"And We send down from the Quran that which is a healing and a mercy to those who believe, and it increases the zaalimoon (wrongdoers) nothing but loss."
[Al-Israa 17:82]

"Ta-Seen [These letters are one of the miracles of the Quran, and none but Allah (Alone) knows their meanings]. These are the Verses of the Quran, and (it is) a Book (that makes things) clear"
[Al-Naml 27:1]

"Verily, We have sent down to you (O Muhammad) the Book (this Quran) for mankind in truth. So whosoever accepts the guidance, it is only for his ownself; and whosoever goes astray, he goes astray only for his (own) loss. And you (O Muhammad) are not a Wakeel (trustee or disposer of affairs, or guardian) over them"
[Al-Zumar 39:4]