Abu Ma'mar (may Allah have mercy on him) narrates: Whenever we heard something from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that we disliked, we would remain silent until he explained it to us. One day Abdullah (may Allah be pleased with him) said to us: "No reward is written for the person afflicted with illness (for it)." This upset us and weighed heavily on us, so he said: "But Allah, the Mighty and Majestic, expiates sins through it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8474