Hadith 17:546
'Abdah ibn Sulayman narrated to us, from Hisham ibn 'Urwah, who said: I read the letters of the Prophet, may Allah bless him and grant him peace, and whenever a subject concluded, he would say: "Amma ba'd" (As for what follows).
حدثنا عبدة بن سليمان عن هشام بن عروة قال قرأت رسائل النبي صلى الله عليه وسلم كلما انقضت قصة قال أما بعد