take into one's confidence

take (someone) into (one's) confidence

To tell someone information with the understanding that they will not reveal what was said. Daniel, we've taken you into our confidence to discuss the direction of the company, and where we see you fitting into it. You're the only person I've taken into my confidence about this, so please don't discuss it with anyone else.
See also: confidence, take

take into one's confidence

Trust someone with a secret, as in She took me into her confidence and admitted that she was quitting next month. This idiom uses confidence in the sense of "trust," a usage dating from the late 1500s.
See also: confidence, take