make this clear is the fact that they agree on a yāʾ or a tāʾ in some passages and differ in others. Thus, they agree in one passage on the reading of the Most High’s words,

“And Allah is not unaware of what they do,”

but differ in two other passages. We have explained that two readings are like two verses: additional readings are like additional verses. However, when the written form is the same and the wording admits both readings, this makes for a more concise script.

The transmission of the Quran rests on memorization by heart, not on written copies. Thus, in an authentic hadith, the Prophet, may Allah bless him and grant him peace, said:

“My Lord said to me, ‘Rise among Quraysh and warn them.’ I said, ‘My Lord, they will then crush my head’—that is, smash it. He said, ‘I will test you and test others through you, and reveal to you a Book that water cannot wash away, which you will recite asleep and awake. Send forth an army, and I shall send twice as many. With those who obey you, fight those who disobey you. Spend, and I shall spend on you.’”

He thus stated that preserving His Book does not depend on a written sheet that water can wash away. Rather, it can be recited in every circumstance, as stated in the description of the Prophet’s community: “Their Gospels are in their hearts.” This contrasts with the People of the Book, who preserve their scripture only in books and can recite it in its entirety only by reading it, not from memory.

An authentic report also establishes that a number of the Companions memorized the entire Quran during the lifetime of the Prophet, may Allah bless him and grant him peace, including the four men from among the Helpers and ‘Abd Allāh ibn ‘Amr. Thus, what we have explained makes it clear that the readings attributed to