It is narrated from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him); he said: "I was travelling with the Prophet (peace and blessings be upon him) while he (peace and blessings be upon him) was riding a donkey called Ya'fur."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17382