Narrated Anas bin Malik: Someone came to Allah's Messenger (ﷺ) and said, "The donkeys have been (slaughtered and) eaten. Another man came and said, "The donkeys have been destroyed." On that the Prophet (ﷺ) ordered a caller to announce to the people: Allah and His Apostle forbid you to eat the meat of donkeys, for it is impure.' Thus the pots were turned upside down while the (donkeys') meat was boiling in them.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ سَلاَمٍ، أَخْبَرَنَا عَبْدُ الْوَهَّابِ الثَّقَفِيُّ، عَنْ أَيُّوبَ، عَنْ مُحَمَّدٍ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم جَاءَهُ جَاءٍ فَقَالَ أُكِلَتِ الْحُمُرُ، ثُمَّ جَاءَهُ جَاءٍ فَقَالَ أُكِلَتِ الْحُمُرُ. ثُمَّ جَاءَهُ جَاءٍ فَقَالَ أُفْنِيَتِ الْحُمُرُ. فَأَمَرَ مُنَادِيًا فَنَادَى فِي النَّاسِ إِنَّ اللَّهَ وَرَسُولَهُ يَنْهَيَانِكُمْ عَنْ لُحُومِ الْحُمُرِ الأَهْلِيَّةِ، فَإِنَّهَا رِجْسٌ. فَأُكْفِئَتِ الْقُدُورُ وَإِنَّهَا لَتَفُورُ بِاللَّحْمِ.
sunnah.com