Musnad Ahmad 27:1953

'Abd al-Samad narrated to us, my father narrated to us, Ayyub narrated to us, from Nafi', from Ibn 'Umar, who said: The Messenger of Allah (may Allah bless him and grant him peace) fasted continuously (without breaking his fast), so the people fasted continuously. He forbade them, so they said: "O Messenger of Allah, but you fast continuously?" He said: "I am not like your state; I am fed and given to drink."