I heard the Messenger of Allah ﷺ say, "Nothing afflicts a believer in his body causing him pain except that Allah wipes away some of his sins because of it."
سمعت رسول الله ﷺ يقول: ما من شيء يصيب المؤمن في جسده يؤذيه إلا كفر الله عنه به من سيئاته.
Imam Ahmad narrated it (16899) from Yaala bin Ubayd, who said, "Talha (meaning ibn Yahya) narrated to us, from Abu Burda, from Muawiya," and he related the same. Hakim also related it (1/347) by this route and said, "Sahih according to the standard of the two Shaykhs." But the correct view is that it meets the standard of Muslim alone, because Talha bin Yahya was only included by Muslim, and moreover there is disagreement about him, though his hadith is hasan.Tabarani related it in Al-Kabir (19/359) and in Al-Awsat (5843) through the route of Yunus bin Bukayr, from Talha bin Yahya with his chain, and he said in Al-Awsat, "No one narrated this hadith from Talha bin Yahya except Yunus bin Bukayr, and no one narrated it from Muawiya except Abu Burda." That is what he said, but Yaala bin Ubayd also related it from Talha bin Yahya, as mentioned above.Haythami mentioned it in Al-Majmu (2/130) and said, "Ahmad and Tabarani related it in Al-Kabir and Al-Awsat, and it contains a story, and the men of Ahmad's narration are the men of the Sahih."I say, the story that Haythami refers to is what Tabarani mentioned in Al-Kabir and Al-Awsat, and what Munziri mentioned in Al-Targhib (5125), and the wording is his, from Ibn Abu Dunya. Abu Burda said, "I was with Muawiya while a physician was treating an ulcer on his back, and he was in pain, so I said to him, 'If one of our young men had done this, we would have blamed him for it.' He said, 'It would not please me to be without it. I heard the Messenger of Allah ﷺ say, "There is no Muslim who is afflicted with any harm in his body except that it becomes an atonement for his sins."'"Tabarani's wording contains omissions, except that Ibn Abu Dunya did not mention this story, but rather confined himself to the wording of the raised hadith, which is his saying ﷺ, "There is nothing that afflicts the believer in his body and harms him except that it atones for his sins through it." He related it in Al-Marad wal-Kaffarat (35) from Muhammad bin Abdul-Rahman, from Yaala bin Ubayd with his chain.As for what is related from Abu Darda as a raised hadith, "Indeed headache and fever continue to afflict the believer, and even if his sin were like the size of Mount Uhud, it would not leave him while he still bears a mustard seed's weight of it," this is daif.Imam Ahmad related it (21728) from Hasan bin Musa, "Ibn Lahia narrated to us, Yazid bin Abu Habib narrated to me, from Muaz bin Sahl bin Anas Juhani, from his father, from his grandfather, that he visited Abu Darda and said, 'With health, not with illness.'" Abu Darda said, "I heard the Messenger of Allah ﷺ say," and he related it.This chain contains Ibn Lahia, who had poor memory and became confused after his books were burned. He erred in this chain in two places. The first is his mention of Muaz bin Sahl, which is a mistake, for there is no narrator by the name of Muaz bin Sahl. Rather, it is Sahl bin Muaz bin Anas, about whom Ibn Hibban said, "His hadith is munkar (unrecognized)." The second is that he added to the chain, "from his grandfather." The correct version is that it is from his father only, as he himself related it, for Imam Ahmad related it (21736) from Hasan, from him, who said, "Zaban narrated to us, from Sahl bin Muaz, from his father, from Abu Darda, that he came to visit him, and Abu Darda said to my father after greeting him, 'With health, not with pain,' repeating this three times, then he said, 'I heard the Messenger of Allah ﷺ say,'" and he related something similar.This chain contains a series of weak narrators, Ibn Lahia, and his teacher Zaban, who is Ibn Faid, and his teacher Sahl bin Muaz. All the chains for this hadith revolve around Ibn Lahia, and for this reason Hafiz Haythami said in Al-Majmu (2/301), "Ahmad and Tabarani related it in Al-Kabir and Al-Awsat, and it contains Ibn Lahia, about whom there is discussion."