Sayyidina Ali (RA) reported that Allah's Messenger (SAW) said, "There are rooms in Paradise from whose interior their outside can be seen ans whose inside can be seen from their outside." A villager stood up and asked, "For whom are they, O Prophet of Allah?" He said, "They are for those who utter good words, feed food, keep fast always and pray Salah for Allah at night when people are asleep."
[Ahmed 19752, Bukhari 4878, Muslim 180,Ibn e Majah186]