Chapter: What Has Been Related About Reward For The Sick
Aishah narrated that: The Messenger of Allah said: The believer is not afflicted by the prick of a thorn or what is worse (or greater) than that, except that by it Allah raises him in rank and removes sin from him.
Abu Sa'eed Al-Khudri (may Allah be pleased with him) narrated that: The Messenger of Allah said: Nothing afflicts the believer, whether fatigue, grief, disease - even a worry that concerns him - except that by it, Allah removes something from his bad deeds.