Silsilah as-Sahihah 1582 — Do not speak ill of illness

It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) went to Umm Sa'ib or Umm Musayyib and said: "What is the matter with you? Why are you trembling?" She said: "It is fever, may Allah not bless it." The Prophet (peace and blessings of Allah be upon him) said: "Do not curse fever, for it removes the sins of the children of Adam just as a bellows removes the impurities of iron."