Abusive husbands.
Sharh al Kabeer by ad-Dardir al Maaliki states:
“(( ولها ) أي للزوجة ( التطليق ) على الزوج ( بالضرر ) وهو ما لا يجوز شرعا كهجرها بلا موجب شرعي وضربها كذلك وسبها وسب أبيها ، نحو يا بنت الكلب يا بنت الكافر يا بنت الملعون كما يقع كثيرا من رعاع الناس ويؤدب على ذلك زيادة على التطليق كما هو ظاهر ..”
“The wife has the right to Khul’ (divorce) from her husband due to harm (Darar), which includes:
– Unjustified abandonment
– Unjustified physical abuse
– Insulting her or her father, such as saying,
“You’re the daughter of a dog,” “You’re the daughter of a disbeliever,” or “You’re the daughter of a cursed person,” as often happens among ignorant people, and he will be disciplined for that in addition to the khul.
(Sharh al-Kabir by al-Dardir, Book of Marriage and Related Issues, Chapter on the Rulings of Nushuz (Disobedience), Volume 2, Page 345, Published by Dar al-Fikr, Beirut.)