Sayyiduna Saeed bin Yasar (may Allah have mercy on him) narrates that he was traveling to Makkah with Sayyiduna Abdullah bin Umar (may Allah be pleased with them). When dawn was near, I dismounted from my ride and performed the Witr prayer. Sayyiduna Abdullah bin Umar (may Allah be pleased with them) said: "Is the Messenger of Allah (peace and blessings be upon him) not a model for you?" I replied, "Why not! By Allah." He then said, "The Messenger of Allah (peace and blessings be upon him) used to perform Witr on the camel itself."
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 78
Hadith Takhrijصحیح بخاری، الوتر، باب الوتر على الدابة، رقم : 999، صحیح مسلم، المساجد ومواضع الصلاة، باب جواز صلاة النافلة علی الدابة في السفر، رقم : 700۔