grain of truth

noun

(idiomatic) Any facts or true statements at all. / (idiomatic) A small piece of true or useful information.

There may be a grain of truth in what he said.

意味（1）

(idiomatic) Any facts or true statements at all.

There's not a grain of truth in what you just told me.

意味（2）

(idiomatic) A small piece of true or useful information.

It may be a tall-tale, but there is a grain of truth to it as well.