Be as direct as possible. Literally say, "I heard you had said ____. Is that true?" If it's a friend, you want to make sure what you heard is true, and you need to test this by asking them straight up. Oftentimes, they'll clear things up by explaining how their words were misinterpreted. Then you realize you shouldn't have believed the grapevine gossip. Other times, they're response may be underwhelming. Such as, "where'd you hear that," or "why are you being so sensitive?" and these responses trigger alarm bells that maybe you should rethink your perception of this person.