How did the unlettered Prophet convey the revelation from the the cave to the Muslims absolutely correctly, even though he is a human who might forget?

Forgetting is human nature, yet Allah specifically distinguished the Prophet (peace be upon him) by not forgetting the Qur'an, except for what Allah willed to abrogate, or what was a temporary forgetfulness followed by a reminder from Allah, as stated in His saying: (We will make you recite, and you will not forget Except what Allah wills) [Al-A'la: 6-7]. Allah also forbade him from hastening to recite the revelation before Jibreel finished it, and Allah guaranteed him the preservation of the Qur'an in his heart, its collection, and its explanation, as in His saying: (Move not your tongue with it to hasten thereby Indeed, upon Us is its collection and its recitation) [Al-Qiyamah: 16-17]. This is consistent with His saying: (Indeed, We have sent down the Dhikr (Qur'an), and indeed, We will be its Guardian) [Al-Hijr: 9].