question #1 Sahih al-Bukhari 1098, Book 18, Hadith 18 : What is the significance of the direction faced during optional prayers while traveling?

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.”