Mishkat al-Masabih 4515
Jabir reported God's messenger as saying:
“There is a medicine for every disease, and when the medicine is applied to the disease it is cured by God’s permission.” 

Muslim transmitted it.
وَعَنْ جَابِرٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لِكُلِّ دَاءٍ دَوَاءٌ فَإِذَا أُصِيبَ دَوَاءٌ الدَّاءَ بَرَأَ بِإِذْنِ اللَّهِ» . رَوَاهُ مُسلم