Musnad Abu Ya'la al-Mawsili 160:105

And with his chain of narration, that the Messenger of Allah (may Allah bless him and grant him peace) said: Allah (Mighty and Majestic is He) said: "If My servant intends a good deed and does not perform it, I record it for him as one good deed. If he performs it, I record it for him as ten good deeds, up to seven hundred times over. And if My servant intends a bad deed and does not perform it, I do not record it against him. If he performs it, I record it against him as one single bad deed."