It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The one who strives for widows and the needy is like the one who strives in the path of Allah." Al-Qa'nabi said: I think he (the Prophet (peace and blessings be upon him)) said: "(He is) like one who stands in prayer without tiring and like one who fasts without breaking his fast."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12666