Sahih Muslim Book - 2, Hadith - 607

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى حَدَّثَنَا عَبْدُ الرَّحْمَنِ حَدَّثَنَا سُفْيَانُ عَنْ الْأَعْمَشِ وَمَنْصُورٍ عَنْ إِبْرَاهِيمَ عَنْ عَبْدِ الرَّحْمَنِ بْنِ يَزِيدَ عَنْ سَلْمَانَ قَالَ قَالَ لَنَا الْمُشْرِكُونَ إِنِّي أَرَى صَاحِبَكُمْ يُعَلِّمُكُمْ حَتَّى يُعَلِّمَكُمْ الْخِرَاءَةَ فَقَالَ أَجَلْ إِنَّهُ نَهَانَا أَنْ يَسْتَنْجِيَ أَحَدُنَا بِيَمِينِهِ أَوْ يَسْتَقْبِلَ الْقِبْلَةَ وَنَهَى عَنْ الرَّوْثِ وَالْعِظَامِ وَقَالَ لَا يَسْتَنْجِي أَحَدُكُمْ بِدُونِ ثَلَاثَةِ أَحْجَارٍ.

It was narrated that Salman said: "The idolators said to us: 'I think that your companion has taught you (everything), he has even taught you how to defecate.' He said: "Yes. He forbade any one of us to clean himself with his right hand, or to face towards the Qiblah, and he forbade us to use dung or bones, and he (s.a.w) said: 'No one of you should clean himself with less than three pebbles."'