Sahih Muslim , Book 21, Hadith 4777 (USC-MSA)

Anas reported: When Allah's Messenger conquered Khaibar, we caught hold of the asses outside the village. We cooked them (their flesh). Then the announcer of Allah's Messenger made the announcement: Listen, verily Allah and His Messenger have prohibited you (the eating of) their (flesh), for it is a loathsome evil of Satan's doing. Then the earthen pots were turned over along with what was in them, and these were brimming (with flesh) at that time.

وَحَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا سُفْيَانُ، عَنْ أَيُّوبَ، عَنْ مُحَمَّدٍ، عَنْ أَنَسٍ، قَالَ لَمَّا فَتَحَ رَسُولُ اللَّهِ صلى الله عليه وسلم خَيْبَرَ أَصَبْنَا حُمُرًا خَارِجًا مِنَ الْقَرْيَةِ فَطَبَخْنَا مِنْهَا فَنَادَى مُنَادِي رَسُولِ اللَّهِ صلى الله عليه وسلم أَلاَ إِنَّ اللَّهَ وَرَسُولَهُ يَنْهَيَانِكُمْ عَنْهَا فَإِنَّهَا رِجْسٌ مِنْ عَمَلِ الشَّيْطَانِ ‏.‏ فَأُكْفِئَتِ الْقُدُورُ بِمَا فِيهَا وَإِنَّهَا لَتَفُورُ بِمَا فِيهَا ‏.‏

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