Is it permissible to benefit from tools and household items belonging to the ex-wife of the husband’s brother, which her husband left behind, and they both abandoned the house mortgaged to the bank, with items in it that they did not retrieve?

It is not permissible to take anything from the house of the husband's sister or to benefit from it without the owner's permission, unless there is a fear of its loss and it is intended to preserve it. The furniture of the marital home includes items that belong to the wife and items that belong to the husband. Therefore, their permission must be sought when disposing of utensils and other items they have left behind, due to the saying of the Prophet, peace and blessings be upon him: "None of you should take the belongings of his brother, neither playfully nor seriously. And whoever takes his brother's stick, let him return it," and his saying: "The wealth of a Muslim person is not lawful [to take] except with the good pleasure of his soul."