Hadith 10:687
Abu Bakr narrated to us, he said: Waki’ narrated to us, from Rabi’, from al-Hasan, regarding a man who says to his wife, "You are divorced" (bi-hishtum): He said: The divorce is binding upon him.
حدثنا أبو بكر قال نا وكيع عن ربيع عن الحسن في رجل يقول لامرأته بهشتم قال يلزمه الطلاق