Sayyiduna Abu Sa'id Khudri and Sayyiduna Abu Hurairah (may Allah be pleased with them) narrate from the Prophet (peace and blessings of Allah be upon him) that he said: "When any Muslim experiences fatigue, illness, anxiety, sorrow, pain, or grief—even to the extent that a thorn pricks him—then Allah, because of that, removes his sins."

It is narrated from Sa'id that he said: I was with Salman when he visited a sick person from the Kindah tribe. When Salman came to the patient, he said: "Glad tidings! Indeed, Allah makes the illness of a believer an expiation (for sins) and a cause of (His) pleasure. And the illness of a wicked person is like when the people of a household tie up a camel and then release it. It does not know why it was tied up or why it was released."

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Prophet (peace and blessings of Allah be upon him) that he said: "A believing man or woman continues to be tested in his body, his family, and his wealth, until he meets Allah in such a state that there remains no sin upon him."

Abu Hurairah (may Allah be pleased with him) narrates that a Bedouin came, so the Prophet (peace and blessings be upon him) said: "Has Umm Mildam ever seized you?" He said: What is Umm Mildam? The Prophet (peace and blessings be upon him) said: "It is heat between the skin and the flesh." (i.e., fever). He said: Never. The Prophet (peace and blessings be upon him) said: "Have you ever had a headache (suda‘)?" He said: What is suda‘? The Prophet (peace and blessings be upon him) said: "It is a wind that enters the head and strikes the veins." (i.e., headache). He said: Never. Then when he stood up, the Prophet (peace and blessings be upon him) said: "Whoever wishes to look at a man from the people of Hell, let him look at this one."