Hadith 10:300
Abu Bakr narrated to us, he said: Ghundar narrated to us, from Shu'bah, from al-Haytham, from Hammad, regarding a man who said to his wife: "You are divorced, if Allah wills." He said: "His exception (istithna) is valid for him." And al-Hakam said the same.
حدثنا أبو بكر قال نا غندر عن شعبة عن الهيثم عن حماد في الرجل قال لأمرأته أنت طالق إن شاء الله قال له ثنياه وقال الحكم مثله