One day 'Umar ibn al-Khattab came into the house of the Prophet to find him lying on a simple mattress which left its marks on his body. Umar started to sob.
'Why are you crying? O 'Umar', said the Prophet.
'I thought of Caesar and Chosroes sitting on thrones of gold, wearing silk. And you are the messenger of Allah, yet here you are sitting on this simple mattress.'

'O Umar', said the Prophet, 'are you not satisfied that they have this world and we have the next?'
So simple and austere were his living habits that he went half-hungry most of the time.
'A'ishah reported that for three consecutive nights, a fire was not kindled in the homes of the Prophet because there was nothing to be cooked. When asked how they managed, she said they depended on water and dates (the two blacks).
Where is the basis for the image of a self-indulgent, luxury-loving ruler with his 'harem' which some critics of the Prophet have contrived to draw for him?
Source: "Sunshine at Madinah"