[Machine] Abu Bakr Al-Asbahani, the Hafiz, informed me about these two narrations. Abu Nasr Al-Iraqi narrated to him that Sufyan ibn Muhammad narrated to him from Ali ibn Al-Hasan, who narrated from Abdullah ibn Al-Waleed, who narrated from Sufyan. Both of them mentioned it, and Sufyan narrated the hadith from Ubaidullah, from Nafi', from Ibn Umar, that he used to dislike relieving himself in groups and it is also narrated from Abu Sa'id Al-Khudri as a Marfu' hadith from a weak chain of narrators.  

أَخْبَرَنِي بِهَذَيْنِ الْأَثَرَيْنِ أَبُو بَكْرٍ الْأَصْبَهَانِيُّ الْحَافِظُ أنبأ أَبُو نَصْرٍ الْعِرَاقِيُّ ثنا سُفْيَانُ بْنُ مُحَمَّدٍ ثنا عَلِيُّ بْنُ الْحَسَنِ ثنا عَبْدُ اللهِ بْنُ الْوَلِيدِ ثنا سُفْيَانُ فَذَكَرَهُمَا وَذَكَرَ حَدِيثَ سُفْيَانَ عَنْ عُبَيْدِ اللهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ أَنَّهُ كَانَ يَأْخُذُ الْحَصَى مِنْ جَمْعٍ كَرَاهِيَةَ أَنْ يَنْزِلَ وَقَدْ رُوِيَ حَدِيثُ أَبِي سَعِيدٍ الْخُدْرِيِّ مَرْفُوعًا مِنْ وَجْهٍ ضَعِيفٍ