Musnad Abu Ya'la al-Mawsili 108:125

Zuhayr narrated to us, Jarir narrated to us, from al-A’mash, from Abu Sufyan, from Jabir, who said: Fever came to the Prophet, may Allah bless him and grant him peace, and asked for permission to enter upon him. He said: "Who are you?" It said: "I am Umm Mildam." He said: "Do you know the way to the people of Quba?" It said: "Yes." He said: "So it went to them, and they became feverish and suffered severe hardship from it." They complained to him and said: "O Messenger of Allah, what we have suffered from the fever!" He said: "If you wish, I will supplicate to Allah and He will remove it from you, and if you wish, it will be a purification for you." They said: "No, rather let it be a purification for us, or an expiation."