Yahya related to me from Malik from Jafar ibn Muhammad from hisfather that Ali ibn Abi Talib said, "When a man takes a vow to abstainfrom intercourse, divorce does not occur immediately. If four monthspass, he must declare his intent and either he is divorced or herevokes his vow . "Malik said, "That is what is done amongus."
USC-MSA web (English) reference: Book 29, Hadith 17
Arabic reference: Book 29, Hadith 1170