Hazrat Abu Umaamah (Radiyallahu Anhu) reports that a Sahaabi (Radiyallahu Anhu) asked  Nabi (Sallallahu Alayhi Wasallam): “What reward is there for a person who fights (in the path of Allah Ta’ala) to gain wealth or prominence?” Nabi (Sallallahu Alayhi Wasallam) replied: “There is no reward for him. Indeed Allah Ta’ala accepts only those actions which are done sincerely for His sake.” (Abu Dawood)