التداوي
A general instruction to actively seek treatment for illness, framing every disease — old age excepted — as having a discoverable cure.
تَدَاوَوْا، فَإِنَّ اللَّهَ لَمْ يَضَعْ دَاءً إِلَّا وَضَعَ لَهُ شِفَاءً، غَيْرَ دَاءٍ وَاحِدٍ: الْهَرَمُ
“Seek treatment, for Allah has not created a disease without also creating a cure for it — except one: old age.” (meaning, not a literal translation)
Scholars including Ibn al-Qayyim cite this as the doctrinal basis for treating medicine and scientific inquiry into disease as religiously encouraged, not fatalistically avoided.