Sura 4:34 - Men are the maintainers of women because Allah has made some of them to excel others and because they spend out of their property; the good women are therefore obedient, guarding the unseen as Allah has guarded; and (as to) those on whose part you fear desertion, admonish them, and leave them alone in the sleeping-places and
beat them; then if they obey you, do not seek a way against them; surely Allah is High, Great.
One "way against them" is simply by a husband saying "I divorce you" 3 times, and it is done under sharia law.
Bukhari (72:715) - A woman came to Muhammad and begged her to stop her husband from beating her. Her skin was bruised so badly that she it is described as being "greener" than the green veil she was wearing. Muhammad did not admonish her husband, but instead ordered her to return to him and submit to his sexual desires.
Sura 24:33: ...But force not your maids to prostitution
when they desire chastity, in order that ye may make a gain in the goods of this life. But if anyone compels them, yet, after such compulsion, is Allah, Oft-Forgiving, Most Merciful (to them),