How do we know the Quran hasn't been changed?

Two tracks: memory and writing

The Quran was preserved in two ways at the same time.

Memory. From the very beginning, the Quran was recited aloud in prayer, and many companions of the Prophet ﷺ memorised it completely. A person who has memorised the whole Quran is called a hafiz, and there are millions of them alive today, in every country. If anyone makes a mistake when reciting publicly, for example in the night prayers of Ramadan, someone in the congregation corrects them straight away.

Writing. The Prophet ﷺ had scribes who wrote down each passage as it was revealed, on whatever material was available: parchment, bone, palm leaves.

Gathered into one book

After many people who had memorised the Quran were killed at the Battle of Yamama, the first caliph, Abu Bakr, asked Zayd ibn Thabit, one of the Prophet’s ﷺ main scribes, to gather the whole Quran into a single written collection. Zayd only accepted a passage if it existed in writing and was confirmed by people who had memorised it.

Around twenty years after the Prophet’s ﷺ death, the caliph Uthman had official copies made from that collection and sent them to the major cities, so that everyone would recite from the same standard text.

What the manuscripts show

Manuscripts from the first century of Islam survive in libraries around the world. In 2015, the University of Birmingham announced that radiocarbon testing dated the parchment of its Quran fragment to between 568 and 645 CE, very close to the Prophet’s ﷺ lifetime. Its text matches the Quran read today.

An honest note on variations

Scholars have always openly recorded small differences in early manuscripts, such as spelling, and the recognised ways of reciting some words (the qira’at), which go back to the Prophet ﷺ himself. These were documented from the earliest centuries and don’t change the Quran’s message. They are part of how the text was carefully transmitted, not evidence that it was altered.

What the Quran says about itself

God promises in the Quran to preserve it:

Indeed, it is We who sent down the Reminder, and indeed, We will preserve it. (meaning of 15:9)

Explain it to a friend

The Quran was never just a book. From day one it was memorised and recited out loud by thousands of people, and it still is: millions of people today know every word by heart. Written copies were standardised within twenty years, and manuscripts dated to the Prophet’s time match what we read today.