[al-Anbiya: 50]

And Allah, Exalted is He, says:

“This is a blessed Book which We have sent down to you, so that they may reflect upon its verses and that people of understanding may take heed.”

And Allah, Exalted is He, says:

“And this is a confirming Book in the Arabic tongue.” [al-Ahqaf: 12]

And Allah, Exalted is He, says:

“And We have sent down to you the Book as a clarification of all things.” [al-Nahl: 89]

And Allah, Exalted is He, says:

“And We have sent down to you the Reminder so that you may make clear to people what has been sent down to them.” [al-Nahl: 44]

And Allah, Exalted is He, says:

“Indeed, it is a revelation from the Lord of the worlds, brought down by the Trustworthy Spirit upon your heart, so that you may be one of the warners, in clear Arabic speech.” [al-Shu'ara: 192]

Thus, in all these verses, Allah, Exalted is He, has declared that it was sent down. At times, He referred to it as a whole, and at other times to its verses. Whoever claims that the Quran is that which is in heaven has opposed Allah and His Messenger, rejected the miracles of His Prophet, and contradicted the righteous predecessors among the Companions and the Successors, as well as those scholars of the Ummah who came after them.