Language:
كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(38)
Chapter: Ghazwa of Khaibar
(38)
باب غَزْوَةُ خَيْبَرَ
Sahih al-Bukhari 4221, 4222

Narrated Al-Bara and `Abdullah bin Abl `Aufa:

That when they were in the company of the Prophet, they got some donkeys which they (slaughtered and) cooked. Then the announcer of the Prophet (ﷺ) said, "Turn the cooking pots upside down (i.e. throw out the meat).

حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ، حَدَّثَنَا شُعْبَةُ، قَالَ أَخْبَرَنِي عَدِيُّ بْنُ ثَابِتٍ، عَنِ الْبَرَاءِ، وَعَبْدِ اللَّهِ بْنِ أَبِي أَوْفَى، رضى الله عنهم أَنَّهُمْ كَانُوا مَعَ النَّبِيِّ صلى الله عليه وسلم فَأَصَابُوا حُمُرًا فَطَبَخُوهَا، فَنَادَى مُنَادِي النَّبِيِّ صلى الله عليه وسلم أَكْفِئُوا الْقُدُورَ‏.‏
Reference : Sahih al-Bukhari 4221, 4222
In-book reference : Book 64, Hadith 261
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 532
  (deprecated numbering scheme)