Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 233
It is narrated on the authority of Abu Huraira that the Messenger of Allah (may peace be upon him) said: The Great and the Glorious Lord said (to angels): Whenever My bondsman intends to corn it an evil, do not record it against him, but if he actually commits it, then write it as one evil. And when he intends to do good but does not do it, then take it down is one act of goodness, but if he does it, then write down ten good deeds (in his record).