Allah Almighty says: “And when Our verses are recited to them as clear evidences, those who do not expect the meeting with Us say, “Bring us a Qur’an other than this or change it.” Say, [O Muhammad], “It is not for me to change it on my own accord. I only follow what is revealed to me. Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day.”
(Surah Yunus: 15)

azZarqaani (may Allah have mercy upon him) said:

“There is nothing to be said after God and His messenger have spoken. Thus, this nation has consensus that there is no involvement of any man in the Nazm (words and word order) of this Quran, not in its style, its phrases, nor even the rules of its recitation. So whoever deviates from this consensus and follows a path other than the path of the believers then God leaves him to what he has chosen, makes his abode the hellfire, and what a horrible destination that is.

And here, we have seen the Quran in this verse prohibiting the Prophet from attempting such a thing in the most stringent manner, tying it to a severe threat; accompanying a painful retribution. So it’s impossible for Ibn Masood or anyone greater than Ibn Masood after this to change a single word from the Quran with a word of his own liking”.

((وَإِذَا تُتۡلَىٰ عَلَیۡهِمۡ ءَایَاتُنَا بَیِّنَـٰتࣲ قَالَ ٱلَّذِینَ لَا یَرۡجُونَ لِقَاۤءَنَا ٱئۡتِ بِقُرۡءَانٍ غَیۡرِ هَـٰذَاۤ أَوۡ بَدِّلۡهُۚ قُلۡ مَا یَكُونُ لِیۤ أَنۡ أُبَدِّلَهُۥ مِن تِلۡقَاۤىِٕ نَفۡسِیۤۖ إِنۡ أَتَّبِعُ إِلَّا مَا یُوحَىٰۤ إِلَیَّ إِنِّیۤ أَخَافُ إِنۡ عَصَیۡتُ رَبِّی عَذَابَ یَوۡمٍ عَظِیمࣲ)).

قال الزرقاني رحمه الله :
وليس بعد كلام الله ورسوله كلام ، كذلك أجمعت الأمة على أنه لا مدخل لبشر في نظم هذا القرآن ، لا من ناحية أسلوبه ، ولا من ناحية ألفاظه ، بل ولا من ناحية قانون أدائه ، فمَن يخرج على هذا الإجماع ، ويتبع غير سبيل المؤمنين : يولِّه الله ما تولى ، ويصله جهنم ، وساءت مصيراً .
وها نحن أولاء قد رأينا القرآن في تلك الآية يمنع الرسول من محاولة ذلك منعاً باتّاً ، مشفوعاً بالوعيد الشديد ، ومصحوباً بالعقاب الأليم ، فما يكون لابن مسعود ، ولا لأكبر من ابن مسعود بعد هذا أن يبدِّل لفظاً من ألفاظ القرآن بلفظٍ من تلقاء نفسه .
“مناهل العرفان في علوم القرآن” (1/188) .