On the authority of Abu Dharr Jundub ibn Junada and Abu Abd ar Rahman Mu'adh ibn Jabal (may Allah be pleased with them both), that the Messenger of Allah* said:
Fear Allah wherever you are, and follow up a bad deed with a good one and it will wipe it out, and behave well towards people.
It was related by at-Tirmidhi, who said it was a good Hadith in numerous of his works.