It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, your Lord is Merciful. Whoever intends a good deed but does not do it, there is written for him from ten times up to seven hundred times, and even many more times than that. And whoever intends an evil deed but does not do it, a good deed is written for him; and if he does it, only one evil deed is written against him, or it is erased. And none is destroyed before Allah except one who is (truly) doomed."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12705