The Case of the Missing Letters

Michael Cook's
The Koran: A Very Short Introduction
Is a scholarly book
Not religious instruction.

He goes into some of the textual difficulties, including the fact that the purely Koranic text is low on vowels.

"Arabic at the time of the rise of Islam had no way of marking short vowels, and only ambiguous ways of marking long ones."

Credit goes to the Phoenicians
For inventing the alphabet.
But vowels came from the Grecians
nd thy'r th bst thng yt!