Laws of Rechilus / 1: 8-9 (92)

8. If one’s friend asks him what another has said about him, he should try evading the issue without lying or speaking rechilus. If this is not possible, it is preferable that he lie rather than speak rechilus, however one is forbidden to swear for this purpose.

9. The prohibition of rechilus is even when one does not mention the name of the person who wronged him, if his friend is able to understand who he is referring to. So too, if one knows what has been said about him, but does not know who the culprit is, one is forbidden to tell him or even hint it to him.