A kernel of truth phrase
A small amount of truth in something such as a story, speech, or statement, particularly when all other elements are invented.
After asking him a few questions, the police concluded there was a kernel of truth in what he said.
After listening to a gripping narrative of her journey up the Amazon, I know there is only a kernel of truth in it.
The origin of this phrase is not clear.
To tell someone the truth about something that they had not understood or received false information
I have to set my wife straight about what happened yesterday.