Collecting the Qur'an into one place

In the years after the Prophet ﷺ died, the Qur'an existed in two forms: in the memories of the people who had learned it, and written on whatever materials had been to hand. There was no single bound collection, because until then there had been no need for one.

Then came the Battle of Yamamah, in which a large number of the qurra' — the reciters, those who carried the Qur'an and taught it — were killed. Umar ibn al-Khattab went to Abu Bakr with a worry: if this happened again, and again, a portion of the Qur'an could be lost with the people who carried it.

Abu Bakr's first reaction, as the reports have it, was hesitation. The Prophet ﷺ had not done this, and doing something the Prophet ﷺ had not done was not a small matter to him. The reports describe Umar returning to the question until Abu Bakr was convinced.

The work was given to Zayd ibn Thabit, who had written revelation down during the Prophet's ﷺ lifetime. Zayd's own reported reaction was that being asked to move a mountain would have been lighter. He gathered what was written and what was memorised, and compiled it into a single collection.

Of everything in Abu Bakr's two years as caliph, this is the decision whose effect reached furthest. It was also the one he was most reluctant to make.