let (someone) off
Definition: to decide not to punish someone, or to give a lighter punishment than expected.
(This phrasal verb has more than one meaning)
E.g.1: She smiled sweetly at the policeman who had stopped her for driving too fast and he let her off with a caution.
E.g.2: I’ll let you off this time, but if you do it again I’ll prosecute you.
This phrasal verb is separated by its object. (E.g.1 and 2)