What is the ruling on the wife's brother or father staying with the wife for several days, given that their financial situation is better than the husband's, which causes the husband to dislike them, but he cannot tell them that out of consideration for his wife's feelings?

Hospitality in Islam is for three days, and anything beyond that is considered charity. It is not permissible for a guest to stay with the host after three days so as not to cause the host to fall into sin. This is if the guest stays after three days without an invitation from the host. However, if the host invites them or it is known that the host does not dislike their stay, then there is no harm in the extended visit.

Therefore, it is not permissible for the wife's father, brother, or any other relatives to stay for a long period in the house of their daughter's husband if that causes him harm or if he has not given them permission to stay. The husband has the right to prevent the wife's parents from visiting her in her marital home if it causes harm, and preventing others besides the parents is even more appropriate.