Shaykh Atiyyah Muhammad Salim | Authentic Statements
On the authority of Salmaan al-Farisee (may Allah be pleased with him) that he said: Have glad tidings! For Allah makes the sickness of the believer an expiation and a seeking of means of attaining His Pleasure, while the sickness of the corrupt, sinful person is like the camel being tied by its owner, then setting him free. He doesn’t know why he was tied, nor why he was set free.
Al-Adab Al-Mufrad, 493, and declared authentic by Shaykh al-Albani.