Good Manner and Prolong silence best among good work

Anas Radiyallahu 'anhu narrates that Rasullullah Sallallahu 'alaihi wasallam met Abu Dhar and said: 

O Abu Dhar! Shall I not tell you of two qualities which are light on the back, and are very heavy on the Scale as compared to others? 

Abu Dhar said: Yes verily, O Rasulallah! 

He said: Adopt good manners and observe prolonged silence. I swear by Him Who has control on the life of Muhammad, none of the deeds performed by any of the creation is as virtuous as these two.