don't let it go any further
Don't reveal this information to anyone else. Greg got the promotion, but don't let it go any further—the boss will officially announce it later today.
Don't let it go any further,
and Don't let it out of this room.Don't tell this secret to anyone else. (Also literal.) This is a strict secret. Don't let it go any further. I'll tell you what you what to know, but don't let it go out of this room.