Maliks Muwatta Book 029, Hadith Number 008.

Section : The 'Irrevocable' Divorce.

Yahya related to me from Malik from Yahya ibn Said from al-Qasim ibn Muhammad that a certain man had taken a slave-girl belonging to somebody else as a wife. He said to her people, "She is your concern," and people considered that to be one pronouncement of divorce.