The Owl vs Bombo (1984)

Original title: 貓頭鷹與小飛象

Sammo and George Lam are partners in crime and they scam some triad big shot out of a load of money and decide to retire. Three years later they both receive letters from Stanley Fung, in which he informs them that he has proof of all their criminal activity and unless they do exactly what he says–he will turn it over to the cops. Fung is an ex-cop himself and is trying to get the goods on the same triad leader that Sammo and George scammed.