What is the religious ruling regarding a husband who promised his second wife that he would favor her in terms of overnight stays and financial support (70% of his life)? Is he obligated to fulfill this promise, even if it leads to injustice towards his first wife, who wishes to reclaim her right to overnight stays?

It is permissible for a wife to waive her right to equal division of time (qasm) and overnight stay (mabit). If she waives it and then retracts her waiver and demands her right, there is a difference of opinion among scholars regarding this. The majority of scholars believe she has the right to retract and demand her right because her right is renewed. However, others, including Ibn al-Qayyim, hold that she does not have the right to retract because the waiver is a binding settlement. If she were allowed to retract, it would lead to prolonged harm.

Accordingly, your first wife has no right to demand the equal division of time if she has waived her right. If she insists, you have the option of divorcing her or giving her a choice.

As for the second wife, you must fulfill the conditions she agreed upon. If she agreed to 70% of your time, then you must adhere to that; otherwise, she has the right to annul the marriage. You are not required to be equitable in the division of time in this case, as it would be unjust to the second wife and a breach of the agreed-upon conditions.

It is advisable to try to reconcile with both wives and appease them to live in peace.