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

سَعِيدٌ فَلَمَّا خَشِيتُ الصُّبْحَ نَزَلْتُ فَأَوْتَرْتُ ثُمَّ لَحِقْتُهُ فَقَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ أَيْنَ كُنْتَ فَقُلْتُ خَشِيتُ الصُّبْحَ فَنَزَلْتُ فَأَوْتَرْتُ فَقَالَ عَبْدُ اللَّهِ أَلَيْسَ لَكَ فِي رَسُولِ اللَّهِ ﷺ أُسْوَةٌ حَسَنَةٌ فَقُلْتُ بَلَى وَاللَّهِ قَالَ فَإِنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُوتِرُ عَلَى الْبَعِيرِ  

I was travelling along with Ibn 'Umar on the way to Mecca. Sa'id said: When I apprehended dawn, I dismounted (the ride) and observed Witr prayer and then again joined him. Ibn 'Umar said to me: Where were you? I said: I apprehended the appearance of dawn, so I dismounted and observed Witr prayer. Upon this 'Abdullah said: Is there not a model pattern for you in the Messenger of Allah ﷺ? I said: Yes, by Allah, and (then) he said: The Messenger of Allah ﷺ used to observe Witr prayer on the camel's back.  

سَعِيدٌ فَلَمَّا خَشِيتُ الصُّبْحَ نَزَلْتُ فَأَوْتَرْتُ ثُمَّ أَدْرَكْتُهُ فَقَالَ لِي ابْنُ عُمَرَ أَيْنَ كُنْتَ فَقُلْتُ لَهُ خَشِيتُ الْفَجْرَ فَنَزَلْتُ فَأَوْتَرْتُ فَقَالَ عَبْدُ اللَّهِ أَلَيْسَ لَكَ فِي رَسُولِ اللَّهِ ﷺ أُسْوَةٌ فَقُلْتُ بَلَى وَاللَّهِ قَالَ إِنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُوتِرُ عَلَى الْبَعِيرِ