Sahih Bukhari

Narrated Sa`id bin Yasar:I was going to Mecca in the company of `Abdullah bin `Umar and when I apprehended the approaching dawn, I dismounted and offered the witr prayer and then joined him. `Abdullah bin `Umar said, ""Where have you been?"" I replied, ""I apprehended the approaching dawn so I dismounted and prayed the witr prayer."" `Abdullah said, ""Isn't it sufficient for you to follow the good example of Allah's Messenger (ﷺ)?"" I replied, ""Yes, by Allah."" He said, ""Allah's Messenger (ﷺ) used to pray witr on the back of the camel (while on a journey).""