My understanding is that the Maturidis say that Allah created a sound and this sound was what was heard by Prophet Musa 'alayhis salam. I could be wrong, however. Perhaps abu Hasan can clarify the Maturidi stance.
Is this Ijma of Ashari Ulama because I know for a fact that Maturidis don't have a concept of Kalam Nafsi. I think there is disagreement on this issue. Have you read the article by Shaykh Hamid Ali on this ?
From Fatawa Hadithiyya: [Rough translation] Question: What is the meaning of Allahs kalam to musa? Can others hear it? Answer: Even though Allah's kalam is not from the same genus of the speech of creation those whom Allah has honored can hear it from His messengers, angels be it with a wasita or not. wama kana libasharin an yukallimahu Allahu illa wahyan (It is not fitting for a man that Allah should speak to him except by inspiration) [Sura Shura, 51] wakallama Allahu moosa takleeman (to Moses God spoke direct) [Sura an-nisa, 164] Some of the Maliki Imams said: Whoever denied that Allah spoke to Musa [a.s.] repentance is sought from him; if he repents that is good otherwise he is to be killed. Some of the latter day Scholars said: In reality all kalam belongs to Allah and ascribing it to others is majaz for if it is pre-eternal, it is His Sifah and if it is emergent then it is from His action because it is from His creation and will, so having said that, the ummah is agreed that Allah is Mutakallim. According to the ash'aris the kalam is established with Allah's entity and is called Kalam nafsi The mu'tazilah denied that and said : Him being Mutakallim is that He created kalam And the ijma' is that He the Exalted spoke to Musa - due to the explicit ayat stating that - this refutes them in their claim of it not being permissible. And they differed in the quality of hearing the kalam nafsi: The people of the dhahir said: we believe in it and we don't speak about it- them intending by this that it is from the mutashabih The Batiniah said: Allah created understanding in Musa within his heart and did not create hearing for him (to hear this kalam). The madhhab of Ahlus sunnah is that Allah created understanding in his heart as well as hearing within his two ears and the rest of his body by which he heard the Kalam of Allah without a voice or letter and without any intermediary. The Mu'tazilah claimed - while traversing upon thier corrupt madhhab in denying kalam nafsi - that Allah created understanding in his heart and a voice in the tree that he heard.
