How should one deal with two wives when one of them relays offensive speech about the other and claims there is undesirable advice, despite attempts to be fair and bring them closer together?

What happens between the wives of a polygamous man is a natural occurrence, caused by the ingrained jealousy in women. The stories of the Mothers of the Believers have demonstrated this. It is expected that wives will try to get closer to their husband by slandering the others or lying to show their love for him, so the husband must deal with this reality. To establish harmony among the wives, it is recommended not to listen to slander against them, to resolve problems by gathering them and listening to them together, not to convey malicious talk from one of them to another, to be keen on absolute justice in everything, and to sometimes use firmness when needed, while admonishing and guiding them to abandon destructive competition.