The Prophet ﷺ was asked about cleansing (after relieving oneself). He said: (One should cleanse oneself) with three stones which should be free from dung. Abu Dawud said: A similar tradition has been narrated by Abu Usamah and Ibn Numair from Hisham.
سُئِلَ رَسُولُ اللَّهِ ﷺ عَنْ الاِسْتِطَابَةِ فَقَالَ بِثَلاَثَةِ أَحْجَارٍ لَيْسَ فِيهَا رَجِيعٌ