Hitman in the Hand of Buddha(1981)

借刀殺人

A country bumpkin arrives to help his brother's rice business. Things get out of hand while a rival company becomes corrupt. The bumpkin, an ace martial artist, fights off the rivals. Angered, the rivals hire a martial arts expert to fight the hero, only to get beaten up himself. The expert send his teacher to hurt the hero and succeeds. The hero is sent to a temple where he learns a new style of kung fu. Now with the skills, our hero is ready to get even.