Sa'id bin Abi Burdah (may Allah be pleased with him) narrates from his grandfather that the Messenger of Allah (peace and blessings be upon him) said: "Charity is due from every Muslim." They said: "If he cannot give it?" (He said:) "Let him work with his hand, benefit himself and give charity." They said: "If he does not have the strength even for that, or cannot do it?" He (peace and blessings be upon him) said: "Then let him help one in desperate need." They said: "If he does not do even that?" He said: "Then let him enjoin good." They said: "If he cannot do even that?" He (peace and blessings be upon him) said: "Then let him refrain from evil, for that is indeed charity for him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7821