If one was to leave out a small sin out of fear of Allah, it is better for him than praying 1000 rak^as from the Sunnah (recommended) rak^as. (This isn't referring to obligatory prayers). The person has to avoid doing this Haraam for the sake of Allah Ta^aalaa alone. If he does it because he was shy because of people around him that saw him commit the sin, than this merit doesn't apply to him. The intention mustbe based on Fear of Allah Ta^aalaa.