>muslims believe historical of al-quran that Allah has already promised to protect the Quran from the change and error that happened to earlier holy texts. Allah states in the Quran in Surat al-Hijr, verse 9:

إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَ وَإِنَّا لَهُ لَحَافِظُونَ

“Indeed, it is We who sent down the Quran and indeed, We will be it’s guardian.”
>We have thus far seen that the way the Quran was taught to the numerous Companions of the Prophet ﷺ prevented it from being subject to the protection of a few people. As verses became widespread across the Islamic world, it was impossible for those verses to be changed without Muslims in other parts of the world noticing and correcting them. Furthermore, during the life of Prophet Muhammad ﷺ, the angel Jibreel would recite the entire Quran with him once a year, during Ramadan. When the Quran was finished being revealed near the end of the Prophet ﷺ’s life, he made sure that numerous companions knew the entire Quran by heart
>During the caliphate of Uthman, from 644 to 656, a new issue regarding the Quran arose in the Muslim community: pronunciation. During the life of the Prophet ﷺ, the Quran was revealed in seven different dialects – qira’as. The dialects differed slightly in their pronunciation of certain letters and words, but the overall meaning was unchanged