Narrated Salim: At night `Abdullah bin `Umar used to offer the prayer on the back of his animal during the journey and never cared about the direction he faced. Ibn `Umar said, "Allah's Messenger (ﷺ) used to offer the optional prayer on the back of his Mount facing any direction and also used to pray the witr on it but never offered the compulsory prayer on it."
The chain is ordered from the source of the saying to the compiler: 1 = the speaker/first transmitter, the following links those who passed it on in turn, and at the bottom al-Bukhari who compiled the work. Click a narrator to list every hadith in which he appears; the number in parentheses is how many hadiths across the collections on this site the narrator appears in.