كتاب الطهارة
1  
The Book of Purification
(7)
Chapter: The Manners of Answering the Call of Nature
(7)
باب قضاء الحاجة
Bulugh al-Maram 101
Narrated Ibn Mas’ud (rad):
The Prophet (ﷺ) went out to answer the call of nature and asked me to bring three stones. I found two stones and searched for the third but could not find it. So I took a dried piece of dung and brought it to him. He took the two stones and threw away the dung and said, “This is a filthy thing”. [Reported by Al-Bukhari]
وَعَنِ ابْنِ مَسْعُودٍ ‏- رضى الله عنه ‏- قَالَ: { أَتَى اَلنَّبِيُّ ‏- صلى الله عليه وسلم ‏-اَلْغَائِطَ, فَأَمَرَنِي أَنْ آتِيَهُ بِثَلَاثَةِ أَحْجَارٍ, فَوَجَدْتُ حَجَرَيْنِ, وَلَمْ أَجِدْ ثَالِثًا.‏ فَأَتَيْتُهُ بِرَوْثَةٍ.‏ فَأَخَذَهُمَا وَأَلْقَى اَلرَّوْثَةَ, وَقَالَ: "هَذَا رِكْسٌ" } أَخْرَجَهُ اَلْبُخَارِيّ ُ 1‏ .‏


‏1 ‏- صحيح.‏ رواه البخاري (156)‏.‏

Reference : Bulugh al-Maram 101
In-book reference : Book 1, Hadith 119
English translation : Book 1, Hadith 107