Al-Adab Al-Mufrad, Book 45, Hadith 5 (In-Book)

Hisham ibn 'Urwa said, "I saw some of the letters of the Prophet, may Allah bless him and grant him peace. After the introduction he said, 'Following on from that'"

حَدَّثَنَا رَوْحُ بْنُ عَبْدِ الْمُؤْمِنِ، قَالَ‏:‏ حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ هِشَامِ بْنِ عُرْوَةَ قَالَ‏:‏ رَأَيْتُ رَسَائِلَ مِنْ رَسَائِلِ النَّبِيِّ صلى الله عليه وسلم، كُلَّمَا انْقَضَتْ قِصَّةٌ قَالَ‏:‏ أَمَّا بَعْدُ‏.‏

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