One reading for everyone

By Uthman's time the Muslim world reached from Egypt to Persia. People in those places had learned the Qur'an from whichever Companion had reached them, and there were differences in how some passages were read.

Within Arabia this had never been a problem. Across an empire it became one. Reports reached Madinah of Muslims from different regions disputing with one another over recitation — not over meaning, but over whose reading was correct.

Uthman's response was to standardise the written text. The collection compiled in Abu Bakr's time was used as the basis; copies were carefully prepared, and sent out to the main centres with reciters who could teach from them.

The same account records the other half of the decision: the personal written copies people had made for themselves were called in and destroyed. It is worth being exact about what that means, because it is often told carelessly. These were private manuscripts of the same revelation, differing in wording and in what their owners had noted on them. Withdrawing them was how the disputes were stopped at the source.

The result is the thing his caliphate is most remembered for, and it is a strange kind of achievement: the reason Muslims anywhere in the world today open the same text is a decision made because people had started arguing.