Musnad Abu Ya'la al-Mawsili 109:174

Ibrahim al-Harawi narrated to us, Ismail bin Ibrahim narrated to us, al-Hajjaj bin Abi Uthman narrated to us, Abu al-Zubayr narrated to me, that Jabir narrated to them, he said: The Messenger of Allah (peace and blessings of Allah be upon him) passed by Umm al-Sa'ib—or Umm al-Musayyib—while she was shivering from fever. He said to her: "What is the matter with you, O Umm al-Sa'ib? You are shivering." She said: "The fever, may Allah not bless it." He said: "Do not curse it, for it removes the sins of the children of Adam just as the bellows removes the dross of iron."