Hazrat ‘Ali (radhiyallahu ‘anhu) said, “Do not speak anything but good regarding Hazrat ‘Uthmaan (radhiyallahu ‘anhu) and the decision that he made concerning the Qur’aan. By Allah, he took this decision concerning the Qur’aan Majeed with the consensus of the Sahaabah (radhiyallahu ‘anhum).” (Saheeh Bukhaari #4987 and Fathul Baari vol. 9 pg. 16)
From this statement, it is clear that Hazrat ‘Ali (radhiyallahu ‘anhu) loved Hazrat ‘Uthmaan (radhiyallahu ‘anhu) and approved of his decision regarding the compilation of the Qur’aan. Hence, the Qur’aan which Hazrat ‘Ali (radhiyallahu ‘anhu) believed in and recited is the very same Qur’aan which the Ahl-us-Sunnah wal-Jamaa‘ah believe in and recite.
As for the Shias, it is their belief that the Qur’aan Majeed is not authentic and that a portion of the Qur’aan Majeed has been lost. They believe that the correct and authentic Qur’aan was memorized by Hazrat ‘Ali (radhiyallahu ‘anhu) and the Mahdi (radhiyallahu ‘anhu) will bring it when he appears.
This can be clearly seen in the two extracts mentioned below. These extracts are from the book Al-Kaafi written by the Shia scholar Kulaini. This book is regarded as one of the four main books of Hadith according to the Shias.
عن جابر قال سمعت أبا جعفر عليه السلام يقول ما ادعى أحد من الناس أنه جمع القرآن كله كما أنزل إلا كذاب وما جمعه وحفظه كما نزله الله تعالى إلا علي بن أبي طالب والأئمة من بعده عليه السلام (أصول كافي – كتاب الحج 1/228)
Jaabir reported that he heard Imam Baaqir saying, “No one can claim that he has compiled the entire Qur’aan as it was revealed by Allah except a liar. The only person to compile it and memorise it as it was revealed by Allah Ta‘ala was Hazrat ‘Ali bin Abi Taalib (radhiyallahu ‘anhu) and the Imams (of the Shias) who succeeded him.”
قرأ رجل على أبي عبد الله عليه السلام وأنا أستمع حروفا من القرآن ليس على ما يقرؤها الناس فقال أبو عبد الله عليه السلام كف عن هذا القرآن اقرأ كما يقرأ الناس حتى يقوم القائم فإذا قام القائم قرأ كتاب الله عز وجل على حده وأخرج المصحف الذي كتبه علي عليه السلام (أصول كافي 2/632)
A man said that someone was reciting the Qur’aan in the company of Imam Ja’far. The narrator said that he heard certain verses in the recitation which were not according to the recitation of the people. Imam Ja’far told the person reciting, “Do not recite like this. Recite as the people recite until the (promised) Mahdi arrives. When the Mahdi arrives, he will recite the Qur’aan according to its original revelation and he will produce the original Qur’aan compiled by Hazrat ‘Ali (radhiyallahu ‘anhu).”
The Ahl-us-Sunnah wal-Jamaa‘ah firmly hold the belief that the Qur’aan Majeed has been perfectly preserved in its original form. If one has to hold the belief that the Qur’aan Majeed is not authentic and that a portion of the Qur’aan Majeed has been lost, as is the belief of the Shias, he will leave the fold of Islam.