Musnad Ahmad 4078

It was narrated that ‘Abdullah (رضي الله عنه) said: l recited to the Messenger of Allah (ﷺ): "And We have indeed made the Qur'an easy to understand and remember; then is there any one who will remember (or receive admonition) (hal min mudhdhakir)?" (al-Qamar 54:17). And the Prophet (ﷺ) said: "hal min muddakir" (i.e., he corrected his pronunciation).