放虎归山的英文：
[Literal Meaning]
release/tiger/return/mountain
to let the tiger return to the mountains

[解释]
把坏人放回老巢，留下祸根。

[Explanation]
to release the evil to its home and cause calamity for the future

[例子]
你们让他回去等于放虎归山，他一定会来报复的。

[Example]
That you let him go is releasing a trouble, and certain that he will come back to revenge.

(fig. ) cause future trouble;blunder into future calamity;(lit. ) let tiger back to mountain
放虎归山