To clean the private parts with stones

Narrated Abu Huraira:

I followed the Prophet while he was going out to answer the call of nature. He used not to look this way or that. So, when I approached near him he said to me, "Fetch for me some stones for ' cleaning the privates parts (or said something similar), and do not bring a bone or a piece of dung." So I brought the stones in the corner of my garment and placed them by his side and I then went away from him. When he finished (from answering the call of nature) he used, them .

حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدٍ الْمَكِّيُّ، قَالَ حَدَّثَنَا عَمْرُو بْنُ يَحْيَى بْنِ سَعِيدِ بْنِ عَمْرٍو الْمَكِّيُّ، عَنْ جَدِّهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ اتَّبَعْتُ النَّبِيَّ ﷺ وَخَرَجَ لِحَاجَتِهِ، فَكَانَ لاَ يَلْتَفِتُ فَدَنَوْتُ مِنْهُ فَقَالَ " ابْغِنِي أَحْجَارًا أَسْتَنْفِضْ بِهَا ـ أَوْ نَحْوَهُ ـ وَلاَ تَأْتِنِي بِعَظْمٍ وَلاَ رَوْثٍ ". فَأَتَيْتُهُ بِأَحْجَارٍ بِطَرَفِ ثِيَابِي فَوَضَعْتُهَا إِلَى جَنْبِهِ وَأَعْرَضْتُ عَنْهُ، فَلَمَّا قَضَى أَتْبَعَهُ بِهِنَّ.