Allaah the Most High said: Verily, We, it is We Who have sent down the Dhikr (i.e. the Qur'ān) and surely We will guard it (from corruption).
{Al-Hijr 15:9}
Say (to the disbelievers): "If you possessed the treasure of the Mercy of my Lord (wealth, money, provision), then you would surely hold back (from spending) for fear of (being exhausted), and man is ever miserly!"
{Sūrah Al-Isrā' 17:100}
... But the Dhālimūn (polytheists and wrongdoers) refuse (the truth — the Message of Islāmic Monotheism, and accept nothing) but disbelief.
{Sūrah Al-Isrā' 17:99}
See they not that Allaah, Who created the heavens and the earth, is Able to create the like of them. And He has decreed for them an appointed term, whereof there is not doubt. ...
That is their recompense, because they denied Our Ayāt (proofs, evidences, verses, lessons, signs, revelations, etc.) and said: "When we are bones and fragments, shall we really be raised up as a new creation?"
{Sūrah Al-Isrā' 17:98}
And he whom Allaah guides, he is led aright; but he whom He sends astray, for such you will find no Auliyā' (helpers and protectors), besides Him, and We shall gather them together on the Day of Resurrection on their faces, blind, dumb and deaf; their abode will be Hell; ...
Say: "If there were on the earth, angels walking about in peace and security, We should certainly have sent down for them from the heaven an angel as a Messenger."
{Sūrah Al-Isrā' 17:95}
And nothing prevented men from believing when the guidance came to them, except that they said: "Has Allaah sent a man as (His) Messenger?"
{Sūrah Al-Isrā' 17:94}
"Or you have a house of Zukhruf (like silver and pure gold), or you ascend up into the sky, and even then we will put no faith in your ascension until you bring down for us a Book that we would read." Say (O Muhammad ﷺ): "Glorified (and Exalted) is my Lord [Allaah) ...
"Or you cause the heaven to fall upon us in pieces, as you have pretended, or you bring Allaah and the angels before (us) face to face;
{Sūrah Al-Isrā' 17:92}
And indeed We have fully explained to mankind, in this Qur'ān, every kind of similitude, but most mankind refuse (the truth and accept nothing) but disbelief.
{Sūrah Al-Isrā' 17:89}
Say: "If the mankind and the jinn were together to produce the like of this Qur'ān, they could not produce the like thereof, even if they helped one another."
{Sūrah Al-Isrā' 17:88}
And if We willed, We could surely take away that which We have revealed to you (i.e. this Qur'ān). Then you would find no protector for you against Us in that respect. Except as a mercy from your Lord. Verily, His Grace to you (O Muhammad ﷺ) is ever great.
{Al-Isrā' 17:86-87}
And they ask you (O Muhammad ﷺ) concerning the Rūh (the spirit). Say: "The Rūh (the spirit) is one of the things, the knowledge of which is only with my Lord. And of knowledge, you (mankind) have been given only a little."
{Sūrah Al-Isrā' 17:85}
Say (O Muhammad ﷺ to mankind): "Each one does according to Shakilatihi (i.e. his way or his religion or his intentions), and your Lord knows best of him whose path (religion) is right."
{Sūrah Al-Isrā' 17:84}
And when We bestow Our Grace on man (the disbeliever), he turns away and becomes arrogant (far away from the Right Path). And when evil touches him, he is in great despair.
{Sūrah Al-Isrā' 17:83}