The Prophet Muhammad (peace be upon him) said: "Every Muslim has to give in charity." The people then asked: "(But what) if someone has nothing to give, what should he do?" The Prophet replied: "He should work with his hands and benefit himself and also give in charity (from what he earns)." The people further asked: "If he cannot find even that?" He replied: "He should help the needy who appeal for help." Then the people asked: "If he cannot do (even) that?" The Prophet said finally: "Then he should perform good deeds and keep away from evil deeds, and that will be regarded as charitable deeds." - Sahih Al-Bukhari, Volume 2, Hadith 524.