Musnad Ahmad 788:47

'Abd al-Rahman narrated to us, Shu'bah narrated to us, from Sa'id ibn Abi Burdah, from his father, from his grandfather, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Upon every Muslim is a charity." He said: "Have you seen if he does not find [anything]?" He said: "He works with his hand, so he benefits himself and gives charity." He said: "Have you seen if he is not able to do that?" He said: "He helps the needy, the distressed." He said: "Have you seen if he does not do that?" He said: "He enjoins good or justice." He said: "Have you seen if he is not able to do that?" He said: "He refrains from evil, for it is a charity for him."