Is it permissible for a husband with multiple wives to chat with one of his absent wives online on the night designated for another wife, thereby neglecting the wife who is present with him?

Speaking with one's wife on the day allocated to her co-wife, without the co-wife's consent, is forbidden (haram). This is because it goes against justice, violates the purpose of overnight stay, and incites jealousy. There is no difference between this and the husband entering upon her during her co-wife's turn, except in a case of urgent necessity.

The husband should consider the feelings of the present wife and choose a different time and place to speak with the absent wife.

The issue of justice among wives during travel differs based on the reason for travel. If the wife travels without her husband's permission, her right to division (of time) is forfeited. However, if she travels with his permission or he sends her, her right is not forfeited. If the wife's right to division remains and her turn passes, the husband must compensate her, unless she waives her right or agrees to a phone conversation as a substitute for the overnight stay.