Sahih al-Bukhari 4173
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · The Ghazwa of Al-Hudaibiya
Narrated Zahir Al-Aslami:
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ ، حَدَّثَنَا أَبُو عَامِرٍ ، حَدَّثَنَا إِسْرَائِيلُ ، عَنْ مَجْزَأَةَ بْنِ زَاهِرٍ الأَسْلَمِيِّ ، عَنْ أَبِيهِ ـ وَكَانَ مِمَّنْ شَهِدَ الشَّجَرَةَ ـ قَالَ إِنِّي لأُوقِدُ تَحْتَ الْقِدْرِ بِلُحُومِ الْحُمُرِ إِذْ نَادَى مُنَادِي رَسُولِ اللَّهِ صلى الله عليه وسلم إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم يَنْهَاكُمْ عَنْ لُحُومِ الْحُمُرِ.
(who was one of those who had witnessed (the Pledge of allegiance beneath) the Tree) While I was making fire beneath the cooking pots containing donkey's meat, the announcer of Allah's Messenger (ﷺ) announced, "Allah's Messenger (ﷺ) forbids you to eat donkey's meat."