Musnad Ahmad 32:1712

'Affan narrated to us, Hammad ibn Salamah narrated to us, he said: Thabit informed us, from Anas ibn Malik, that the Messenger of Allah (peace and blessings of Allah be upon him) fasted continuously (without breaking his fast) in Ramadan. Some of his companions fasted continuously as well, and the Prophet (peace and blessings of Allah be upon him) was informed of that. The Prophet (peace and blessings of Allah be upon him) said: "If the month were extended for me, I would have fasted continuously in a way that would make those who go to extremes abandon their extremism. I spend my time while my Lord feeds me and gives me to drink."