хүнийг хазан нохой шүдээ арзайлгахгүй
[2-3-1-3]日本語
人を噛んだ犬は歯をむき出しにしない
英語
A dog that has bitten someone doesn't bare its teeth [again].
備考
idiom: one who has already done real harm doesn't need to threaten first -- true danger gives no warning