Hadith 3874
Narrated Abu al-Darda: The Prophet ﷺ said: Allah has sent down both the disease and the cure, and He has appointed a cure for every disease, so treat yourselves medically, but use nothing unlawful.
Hadith 4344
Narrated Abu Saeed al-Khudri: The Prophet ﷺ said: The best fighting (jihad) in the path of Allah is (to speak) a word of justice to an oppressive ruler.