المستدرك على الصحيحين
Al Mustadrak ala al‑Sahihayn
كِتَابِ الْإِمَامَةِ وَصَلَاةِ الْجَمَاعَةِ
Book of Leading the Prayer and Congregational Prayer
كَانَ النَّبِيُّ - صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ - لَا يَعْلَمُ خَتْمَ السُّورَةِ حَتَّى تَنْزِلَ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ
The Prophet (peace and blessings be upon him) would not know the end of a surah until "In the name of Allah, the Most Gracious, the Most Merciful" was revealed
Hadith Number: 939N
سالت ابا زكريا العنبري - وحدثنا به عن ابي عبد الله البوشنجي - عن حذف السلام، قال: ان لا يمد السلام ويحذفه.
I asked Abu Zakariya al-Anbari (and he narrated it to us from Abu Abdullah al-Bushanji) about hadhf (shortening) in the salam. He said: It means not to draw out the salam, but to keep it short.
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