Good Manners and Form (Al-Adab)
Bukhari :: Book 8 :: Volume 73 :: Hadith 35
Narrated Safwan bin Salim:
The Prophet said "The one who looks after and works for a widow and for a poor person, is like a warrior fighting for Allah's Cause or like a person who fasts during the day and prays all the night." Narrated Abu Huraira that the Prophet said as above.