Bulugh al-Maram 1 The Book of Purification كتاب الطهارة 119

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).

Narrated Ibn Mas’ud (rad): The Prophet (صلى الله عليه وسلم) 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]