Ask any muslim if he can imagine islam without muhammad.Yeah so crucial that he is mentioned 4 times in the Qur'an
Good luck on that.
Remember this basic phrase muslims say.
It is the very foundation of their faith...
https://www.bbc.co.uk/religion/religions/islam/practices/shahadah.shtml#:~:text="There is no God but,that Muhammad is his prophetThere is no god but allah, and muhammad is his messenger."