never tell tales out of school
Do not share secrets or spread rumors with other people, as doing so will likely cause problems for someone else and will alienate you from them. Hey, I heard what you were saying at the bar the other night. Here's a tip: Never tell tales out of school about your co-workers, or you aren't likely to have any friends here before long.
Never tell tales out of school.
Prov. Do not tell secrets; do not gossip. Fred: I just learned something really scandalous about the president of our company. Ellen: Well, I don't want to hear it. You shouldn't tell tales out of school.