Hadith 10:277
Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Hisham, from al-Hasan, regarding a man who writes to his wife [a letter] of divorce, then it occurs to him to keep the letter: He said: It is nothing as long as he does not speak [the words]. And if he sends it to her, she begins her waiting period from the day the letter reaches her.
حدثنا أبو بكر قال نا عبد الأعلى عن هشام عن الحسن في الرجل يكتب إلى امرأته بطلاقها ثم يبدو له أن يمسك الكتاب قال ليس بشيء ما لم يتكلم وإن بعث إليها اعتدت من يوم ياتيها الكتاب