Sahih al-Bukhari 4221
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · Ghazwa of Khaibar
Narrated Al-Bara and `Abdullah bin Abl `Aufa:
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.
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).