كتاب الطهارة
3  
Purification
(3a)
Chapter: How to act when relieving oneself - Section 1
(2)
باب آداب الخلاء - الفصل الأول
Mishkat al-Masabih 341
Abu Huraira reported God’s messenger as saying, "When anyone performs ablution he must clear his nose, and when anyone wipes himself with stones he must make use of an odd number.” (Bukhari and Muslim.)
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: (قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: مَنْ تَوَضَّأَ فَلْيَسْتَنْثِرْ وَمَنِ اسْتَجْمَرَ فليوتر "
  مُتَّفَقٌ عَلَيْهِ   (الألباني) حكم   :
Reference : Mishkat al-Masabih 341
In-book reference : Book 3, Hadith 53