Let him off this time.

饶他这回吧。

《新英汉大辞典》

You have let him off lightly.

你轻易地放过了他。

youdao

I can't let him off lightly.

我不能就这么便宜了他。

youdao

So the one person who didn't we'll let him off for today.

没选α的人以后要注意了啊

耶鲁公开课 - 博弈论课程节选

This report doesn't let him off the hook, but it impales others alongside him.

BBC: Carrying on banking

Polygamy is legal in South Africa, and acceptable in his Zulu culture, but that doesn't let him off the hook in the comedy clubs.

WSJ: South Africa Gets Some Comic Relief

Anti-Thaksin groups suspect that General Surayud is seeking a deal with Mr Thaksin that would let him off with no more than a temporary ban from politics and some tax-dodging fines in return for not making trouble.

ECONOMIST: Now the hot season really begins