The Qur'an is the pure word of God. Not one word therein is not divine, and that is why it will forever remain a miracle in its self. Not a single word has been deleted from its text. And it is noteworthy that the Holy Prophet's life, the history of the Arabs and the events which occurred during the period of the revelation of the Quran are not mingled with the Divine Verses of the Qur'an, as is the case with the Bible. The Book has been handed down to our age in its complete and original form since the time of Prophet Muhammad (peace be upon him). From the time the Qur'an was being revealed, the Holy Prophet (peace be upon him) had dictated its text to his scribes, who wrote it on animal skins, the back of tree, and other forms of slates available to them. Whenever some Divine Message was revealed, the Holy Prophet (peace be upon him) would call a scribe and dictate its words to him. The written text was then read out to the Holy Prophet (peace be upon him), who, having satisfied himself that the scribe has committed no error of recording, would put the manuscript in safe custody.
The Holy Prophet (peace be upon him) used to instruct the scribe about the sequence in which a revealed message was to be placed in a particular Surah (chapter). In this manner, the Holy Prophet (peace be upon him) continued to arrange the text of the Qur'an in a systematic order till the end of the chain of revelations. Again, it was ordained from the beginning of Islam that a recitation of the Holy Qur'an must be an integral part of worship. Hence the illustrious Companions would commit the Divine verses to memory as soon as they were revealed. Many of them learned the whole text and a far larger number had memorized different portions of it.
Method of preservations of the Quran during the Prophet's time
Although, Allah has promised to safe guard the Qur'an from human manipulation, the process of its preservation can be divided into two; during the life time of the Prophet (peace be upon him) and after his demise.
Allah says in the Qur'an;
(إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَ وَإِنَّا لَهُ لَحَافِظُون)
"Indeed, it is We Who sent down the Qur'an and indeed, We will be its guardian." (Q15:9)
So, Allah the Almighty has taken full responsibility of preserving the Qur'an in the very first place, with a divine protection from Him before any other form of protection known to us.
Besides, those of the Companions (may Allah be pleased with them) who were literate used to keep a written record of several portions of the Holy Qur'an. In this manner, the text of the Holy Qur'an had been preserved in four different ways during the lifetime of the Holy Prophet (peace be upon him):
a) The Holy Prophet (peace be upon him) had the whole text of the Divine Messages from the beginning to the end committed to writing by the scribes of revelations.
b) Many of the Companions learned the whole text of the Qur'an, every syllable of it, by heart.
c) All the illustrious Companions, without an exception, had memorized at least some portions of the Holy Qur'an, for the simple reason that it was obligatory for them to recite it during worship.
d) A considerable number of the literate Companions kept a private record of the text of the Qur'an and satisfied themselves as to the purity of their record by reading it out to the Holy Prophet (peace be upon him).
Method of preservations of the Quran after the demise of the Prophet (peace be upon him)
It is an incontrovertible historical truth that the text of the Holy Qur'an extant today is, syllable for syllable, exactly the same as the Holy Prophet (peace be upon him) had offered to the world as the Word of God. After the demise of the Holy Prophet (peace be upon him), the first Caliph Abu Bakr (may Allah be pleased with him) assembled all the Huffaz (memorizers of the Holy Qur'an) and the written records of the Holy Qur'an and with their help had the whole text written in Book form. This book was kept under the custody of Hafsah, the wife of the Prophet (peace be upon him) and the daughter of Umar bin al-Khattab (may Allah be pleased with them all). Then, during the time of Uthman (may Allah be pleased with him) copies of this original version were made and officially dispatched to the Capitals of the Islamic World. Two Of these copies exist in the world today, one in Istanbul and the other in Tashkent. Whosoever is so inclined may compare any printed text of the Holy Qur'an with those two copies, he shall find no variation.
And how can one expect any discrepancy, when there have existed several million Huffaz (memorizers of the Holy Qur'an) in every generation since the time of the Holy Prophet (peace be upon him) and in our own time? Should anyone alter a syllable of the original text of the Qur'an, these Huffaz would at once expose the mistake. A fulfillment of Allah's promise to guard and protect the Qur'an against any distortion or manipulation.
In the last century, an Institute of Munich University in Germany collected FORTY-TWO THOUSAND copies of the Holy Qur'an including manuscripts and printed texts produced in each period in the various parts of the Islamic World. Research work was carried out on these texts for half a century, at the end of which the researchers concluded that apart from copying mistakes, there was no discrepancy in the text of these forty-two thousand copies, even though they belonged to the period between the 1st Century of the Hijrah to 14th Century Hijrah and had been procured from all parts of the world. This Institute, alas! perished in the bombing attacks on Germany during World War II, but the findings of its research project survived.
Another point that must be kept in view is that the word in which the Qur'an was revealed is a living language in our own time. It is still current as the mother tongue of about a hundred million people from Iraq to Morocco. In the non-Arab world too, hundreds of thousands of people study and teach this language.
A modern Arabic-speaking person can comprehend the Holy Qur'an with as much proficiency as did the Arabs of fourteen centuries ago. This, then, is an important attribute of Muhammad (peace be upon him), which is shared by no other Prophet or Leader of Religion. The Book which God revealed to him for the guidance of mankind is today in its original language without the slightest alteration in its vocabulary.