It is impossible to provide a direct download link or host a copyrighted ROM file for God of War III (or any other commercial game) due to copyright laws and DMCA regulations. Distributing the ISO file for Sony PlayStation 3 (or PS4/PC via emulation) without permission from Sony Interactive Entertainment and Santa Monica Studio constitutes piracy.
Given the difficulty of emulation and legal risks of downloading an ISO, Sony provides three legitimate methods to play God of War III today. God of War III ROM -ISO- Download per Sony Play...
If you want legal options for playing God of War III, here are lawful alternatives: It is impossible to provide a direct download