As-Salaam alaikum,
Addressing the Noble Prophet Muhammad, Sallallahu alaihi Wasallam,
the Qur'an says:--"Truly thou art of an exalted (azim) character (68:4) And it was lost on no one that the Qur'an uses the same adjective to refer to itself "the Mighty (azim) Qur'an" (15:87)

The exaltedness of the Prophet's character drives from the fact that he had assimilated the Qur'an into his very being. This is how a significant portion of the 'Ulama have understood the Prophet's wife A'isha, may Allah be pleased with her, when she was asked about his character after his death. She replied, "Have you not read the Qur'an? His character was the Qur'an." (Sunan Ahmad 10, No. 25,240)

Indeed, among all of Allah's servants, the one who had the most exalted character was/is Muhammad, literally 'the praised one', also called Ahmad, 'the most praiseworthy' (61:6). If the Qur'an calls the Prophet both "Muhammad" and "Ahmad", that is because his character conforms to Allah's "Character", which is to say that his character was the Qur'an, which is Allah's Speech and Self-Expression.