The Mihna, the inquisition the caliph al-Ma'mun launched in 833 CE to force acceptance of the Mu'tazila doctrine that the Quran was created, left every later Sunni school answering the same question: is God's own speech, the Quran as recited, part of God's eternal nature or a thing God made in time. Maturidi theology answers with a distinction later writers called kalam nafsi, the inner word. God's speech as an eternal divine attribute, the argument runs, is uncreated and outside time, exactly as God's other attributes, knowledge or power, are uncreated. What is created is the recitation, the spoken and written Quran a reader encounters, the sounds and letters that carry the eternal meaning into human time.
That distinction let Maturidi theologians affirm the same conclusion Ash'ari and Athari theologians reached by different routes, that the Mu'tazila were wrong to call the Quran created, while giving a more precise account of exactly what remains uncreated and what does not. It also let them answer a fair objection: if the Quran is simply and wholly uncreated, how can it exist as ink on a page or a voice in a room, both plainly temporal things. Kalam nafsi was the school's way of holding the traditional conclusion without leaving that question unanswered, a piece of technical theology built directly out of the controversy that had already cost Ahmad ibn Hanbal his freedom.