Arabic (Original)
حَدَّثَنَا عَبْدُ الْوَهَّابِ أَخْبَرَنَا هِشَامٌ عَنْ حَمَّادٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ سَعْدٍ مَوْلَى عُمَرَ بْنِ الْخَطَّابِ أَنَّهُ أَبْصَرَ عَبْدَ اللَّهِ بْنَ عُمَرَ يُصَلِّي عَلَى رَاحِلَتِهِ لِغَيْرِ الْقِبْلَةِ تَطَوُّعًا فَقَالَ مَا هَذَا يَا أَبَا عَبْدِ الرَّحْمَنِ قَالَ كَانَ نَبِيُّ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَفْعَلُهُ.
English Translation
Abd al-Wahhab told us: Hisham informed us, from Hammad, from Abd al-Rahman ibn Sa'd, the freedman of Umar ibn al-Khattab: that he saw Abdullah ibn Umar praying voluntarily on his mount, not facing the qiblah, and said: What is this, O Abu Abd al-Rahman? He said: The Prophet of Allah, peace and blessings be upon him, used to do it.