It is narrated from Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him) say: "It is not lawful to eat the meat of horses, mules and donkeys."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3811
Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) said: I went on a military expedition with the Messenger of Allah (peace and blessings be upon him), and the Jews came to the Messenger of Allah (peace and blessings be upon him) and complained that the people had hastily entered their enclosures. So the Messenger of Allah (peace and blessings be upon him) sent me, and I announced among the people that the congregational prayer was about to be held, and that none but a Muslim will enter Paradise. When the people had gathered, the Messenger of Allah (peace and blessings be upon him) stood up and said: "What is the matter with the Jews, that they complain that you have hastened into their enclosures? Behold! The property of those under covenant is not lawful without right, and forbidden to you are the domesticated donkeys and their horses, and every predatory animal with fangs and every bird with talons is also forbidden."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3812
A similar hadith is also narrated from Sayyiduna Khalid bin al-Walid (may Allah be pleased with him), except that it has this addition: "Behold! Let no man, reclining on his couch, say: 'Whatever we found lawful in the Book of Allah, that alone we have made lawful, and whatever we found forbidden, that alone we have made forbidden.' Behold! I make the property of those under covenant forbidden to you." (The narrator then narrated the full hadith.)
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3813
Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "O Khalid, announce among the people that the congregational prayer is about to be held, and that none but a Muslim soul will enter Paradise." Then he (peace and blessings be upon him) went out and led the prayer at midday.
Then he (peace and blessings be upon him) stood among the people and said: "I do not make the property of those under covenant lawful without right. Perhaps one of you, reclining on his couch, will say: 'Whatever we found lawful in the Book of Allah, the Mighty and Majestic, that alone we have made lawful, and whatever we found forbidden, that alone we have made forbidden.' And I make the property of those under covenant forbidden to you without right."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3814