Musnad Ahmad 1193:2

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Husayn, from Abu ‘Ubaydah ibn Hudhayfah, from his paternal aunt Fatimah, that she said: We came to the Messenger of Allah, may Allah bless him and grant him peace, to visit him among some women. There was a water skin hanging towards him, its water dripping upon him due to the intensity of what he was experiencing from the heat of the fever. We said: "O Messenger of Allah, if you were to call upon Allah, He would heal you." The Messenger of Allah, may Allah bless him and grant him peace, said: "Indeed, among the people most severely tested are the prophets, then those who are closest to them, then those who are closest to them, then those who are closest to them."