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كتاب الجهاد والسير
56  
Fighting for the Cause of Allah (Jihaad)
(18)
Chapter: To take a bath after fighting
(18)
باب الْغَسْلِ بَعْدَ الْحَرْبِ وَالْغُبَارِ
Sahih al-Bukhari 2813

Narrated `Aisha:

When Allah's Messenger (ﷺ) returned on the day (of the battle) of Al-Khandaq (i.e. Trench), he put down his arms and took a bath. Then Gabriel whose head was covered with dust, came to him saying, "You have put down your arms! By Allah, I have not put down my arms yet." Allah's Messenger (ﷺ) said, "Where (to go now)?" Gabriel said, "This way," pointing towards the tribe of Bani Quraiza. So Allah's Messenger (ﷺ) went out towards them .

حَدَّثَنَا مُحَمَّدٌ، أَخْبَرَنَا عَبْدَةُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم لَمَّا رَجَعَ يَوْمَ الْخَنْدَقِ وَوَضَعَ السِّلاَحَ وَاغْتَسَلَ، فَأَتَاهُ جِبْرِيلُ وَقَدْ عَصَبَ رَأْسَهُ الْغُبَارُ فَقَالَ وَضَعْتَ السِّلاَحَ، فَوَاللَّهِ مَا وَضَعْتُهُ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ فَأَيْنَ ‏"‏‏.‏ قَالَ هَا هُنَا‏.‏ وَأَوْمَأَ إِلَى بَنِي قُرَيْظَةَ‏.‏ قَالَتْ فَخَرَجَ إِلَيْهِمْ رَسُولُ اللَّهِ صلى الله عليه وسلم‏.‏
Reference : Sahih al-Bukhari 2813
In-book reference : Book 56, Hadith 29
USC-MSA web (English) reference : Vol. 4, Book 52, Hadith 68
  (deprecated numbering scheme)