Sahih Muslim, Chapter: Faith (Kitab Al Iman)

that the Messenger of Allah (may peace be upon him) observed: Allah, the Great and Glorious, said: Whenever my bondsman intends to do good, but does not do it, I write one good act for him, but if he puts it into practice I wrote from ten to seven hundred good deeds in favour of him. When he intends to commit an evil, but does not actually do it, do not record it. But if he does it, I write only one evil.