We believe the Qur’an which is now at the hands of the Muslims, is the exact and unaltered copy of that which was revealed to our prophet Muhammad nothing less and nothing more .A group of trustworthy scribes chosen by the prophet himself took note of the revelations from the very beginning up to the end, and Muslims had it a duty of must, to read and recite the verses by day and night. A large group of Muslims committed the book to memory and a group of them had it on the scrolls.
Those who had the book in their memory and those who could recite it for the others, had always had a very respectful position among the believers. Such customs and else, prevented the least amount of changes or any alteration to take place in the book. Additionally God Himself has promised and guaranteed to look after His book and keep it safe and secure until the end:
We have without doubt, sent down the Qur’an, and We will assuredly guard it. (Holy Qur’an, 15:9)
All the learned and researchers in Islam, whether Shia or Sunni, agree that even the slightest alteration has not been made to this Holy Book. Some literate persons, discuss some rare and obscure tradition (hadith) that may mean that some changes have taken place, but the highest majority of those who have the knowledge of Islam, reject that, taking it be false and the mistake of some unaware commentators. Such improvident who lack forethought, by such false ideas strike upon the validity of the most important Divine Book, in contrast to the belief of all the learned Muslims of different sects, which maintain that the Holy Qur’an is unaltered for the least word. These unwise friends, water the mills of the enemy through their ignorance and bring into question the book which is sent by Allah, and has been promised to be guarded by Allah.
If we carefully study the ways that the book was revealed to the prophet and collected by the chosen scribes, and how it was guarded, written, memorized and recited by so many firm and true believers, no doubt remains as to any alteration or the change of even an epsilon in the whole work. On the other hand, of the imaginary or assumed Holy Qur’an with some alteration, not ever a copy exists anywhere, or in any hand, so as to differ with the famous Holy Qur’an which all the Muslims hold as their sacred divine book. Today the Holy Qur’an is found in every house and in every library.
Even those Qur’ans written several hundred years ago are kept in our museums and those in the non-Islamic countries too, and no one can find the least differences in all the existing Qur’ans throughout the world. Today the roads to investigations are open to all, and anyone who doubts, may look for it himself and make sure that the Holy Qur’an has not been altered in the least.
So announce glad tidings to My Servants, to those who listen to My precepts, and follow what is the best in them. Those are the ones that Allah has guided and those are endued with understanding. Holy Qur’an, 39:17
Today in our religious schools the knowledge of the Holy Qur’an is extensively taught, and one of the most important of our lessons in this field is the inability to change the Holy Qur’an.