He is a prophet and not a poet and therefore his Koran is to be seen as Divine Law, and not as a book of a human being made for education or entertainment.

On Muhammad, in Johann Wolfgang Goethe, Noten und Abhandlungen zum West-östlichen Diwan (1958), WA I, 7, 32; translator unknown. Actual quotation in context: "He [Muhammad] vehemently asserts and protests that he is a prophet and not a poet; furthermore, that his Qur'an is to be regarded as divine law, not as a human book meant to instruct or to entertain." West-Eastern Divan: Complete, annotated new translation by Eric Ormsby (Gingko Library, 2019).