let somebody off the hook
let (one) off the hook
To pardon, release, or allow one to escape from blame, responsibility, obligation, or difficulty. At first, Sam was suspected of stealing money from the safe, but he was let off the hook after security camera footage showed it was someone else. I was meant to spend the weekend cleaning out the garage, but my wife let me off the hook so I could go on the big fishing trip with my buddies.
let somebody off the ˈhook(informal) allow somebody to escape from a difficult situation or punishment: We’ll let you off the hook this time, but if you make any more mistakes like that, you’ll lose your job. ♢ There won’t be time for me to read my report to the committee, so that’s let me off the hook.
This expression refers to a fish escaping after it has been caught.