Shemiras Halashon Halachos
Hilchos Rechilus, chapter 8, section 1 Dust of Rechilus
Many things are forbidden because of dust of rechilus. For example, someone asks of someone and is answered: Be quiet, I don't want to say what happened, [or] if one tells how a person's words hinted one had done something wrong. This is dust of rechilus.
Hilchos Rechilus, chapter 8, section 2 3 Another example is if one praises a person in a way that the listener resents and harm can come of it. Therefore, I think one must be careful not to praise a person to his partner (or a husband to his wife) that he gave one a loan or charity or good wages and suchlike, for this often makes the partner or wife resentful of what they perceive as wasting money and can lead to controversy.
If a person refuses to do one a favor, one should not say to him: Why did you do this same favor to so and so who told me about it, for this can lead to resentment against that person for revealing that he did the favor as people now bother him to help them as well.