Tib e Nabvi Prophetic Medicine

And thy Lord taught the Bee to build its cells in hills, on trees, and in (men's) habitations;
Then to eat of all the produce (of the earth), and find with skill the spacious paths of its Lord: there issues from within their bodies a drink of varying colours, wherein is healing for men: verily in this is a Sign for those who give thought.
— Quran, sura 16 (An-Nahl), ayat 68-69

Muhammad's firm belief in the existence of a cause and a cure for every disease is described in many hadith along the lines of the below

Make use of medical treatment, for Allah has not made a disease without appointing a remedy for it, with the exception of one disease, namely old age.
— Abu Dawood, Sunan Abu Dawood