Some claim that Allah ﷻ’s attribute of speech is composed of uncreated utterances pronouncing the Arabic words written on the Mushaf. We argue that this impossible, because such pronunciations exist contingently, what is contingent depends on a creator to have brought it into existence, and Allah ﷻ’s attributes cannot be created.
The pronunciations of letters are contingent because they are sequential. When you utter the Arabic word “Allah” for example, the “A” sound emerges before the “L” sound, and the “L” sound emerges before the “Ah” sound. And since each of the sounds that the word “Allah” is comprised of began to exist, the Arabic word “Allah” itself began to exist and is need of a creator. The same applies to any other sequence of sounds or letters.
For the same reason, all the other utterances pronouncing the Arabic words of the Mushaf exist contingently, and are in need of a creator.
And if it is asked: “what then is the relation between the Arabic phrases Muslims recite every day, and Allah ﷻ’s attribute of Speech?”
The response: those Arabic phrases express meanings that were eternally signified by Allah ﷻ, by virtue of His being attributed with Speech. More on the distinction between Self-Speech and the utterances which express it here.
Allah ﷻ created Arabic words which express the meanings that He eternally signified, and made Jibril (عليه السلام) aware of them. Jibril was then commanded to deliver those words to Prophet Muhammed ﷺ. And they have reached us through him ﷺ by mass transmission.
 How Jibril (عليه السلام) was made aware of them is a secondary matter. It could have been that Allah ﷻ created sounds expressing those words to Jibril. It could have been that Allah ﷻ created carvings of those Arabic words onto the Preserved Tablet, which Jibril then read. It could have been some other way.
What is important is to realize that no matter the manner through which Jibril was made aware of those Arabic words, those Arabic words are necessarily created.