猛虎归山，蛟龙入海 (猛虎歸山，蛟龍入海) měng hǔ guī shān jiāolóng rù hǎi

měng hǔ guī shān jiāolóng rù hǎi phrase a fierce tiger returns to the mountain, a dragon goes into the sea
Domain: Proverb 谚语
Notes: After releasing a tiger or dragon they will go back to their old ways, so an evil-doer cannot be set free without consequences (Guoyu '猛虎歸山，蛟龍入海')