Have Taqwa (fear) of Allah wherever you may be, and follow up a bad deed with a good deed which will wipe it out, and behave well towards the people.
On the authority of Abu Dharr Jundub ibn Junadah, and Abu Abdur-Rahman Muadh bin Jabal (may Allah be pleased with them), that the Messenger of Allah (peace and blessings of Allah be upon him) said:
It was related by at-Tirmidhi, who said it was a Hasan (good) Hadeeth, and in some copies it is stated to be a Hasan Saheeh hadeeth.