Sahih Bukhari, Chapter: Fasting

The Prophet (SAW) made a bond of brotherhood between Salman and Abu Darda. Salman paid a visit to Abu Ad-Darda and found Um Ad-Darda dressed in shabby clothes and asked her why she was in that state. She replied, "Your brother Abu Ad-Darda is not interested in (the luxuries of) this world." In the meantime Abu Darda came and prepared a meal for Salman. Salman requested Abu Ad-Darda to eat (with him), but Abu Ad-Darda said, "I am fasting." Salman said, "I am not going to eat unless you eat." So, Abu Ad-Darda ate (with Salman). When it was night and (a part of the night passed), Abu Ad-Darda got up (to offer the night prayer), but Salman told him to sleep and Abu Ad-Darda slept. After sometime Abu Darda again got up but Salman told him to sleep. When it was the last hours of the night, Salman told him to get up then, and both of them offered the prayer. Salman told Abu Ad-Darda, "Your Lord has a right on you, your soul has a right on you, and your family has a right on you; so you should give the rights of all those who has a right on you." Abu Ad-Darda came to the Prophet and narrated the whole story. The Prophet said, "Salman has spoken the truth."