The Book Pertaining to Piety and Softening of Hearts (Kitab Al-Zuhd wa Al-Raqa'iq)
Muslim :: Book 42 : Hadith 7094
'A'isha reported this hadith through other chains of transmitters also (and the words are) that Allah's Messenger (may peace be upon him) died (in a state) when the people could afford to eat only the dates and water.