Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) came to Umm Sa’ib or Umm Musayyib and asked: "Umm Sa’ib! What has happened to you? You are trembling." She replied: "It is fever, may Allah not bless it." The Prophet (peace and blessings be upon him) said: "Do not speak ill of fever, for it removes the sins of the children of Adam just as a bellows removes the impurities of iron."