The Messenger of Allah ﷺ said: When any of you goes to relieve himself, he should take with him three stones to cleans himself, for they will be enough for him.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا ذَهَبَ أَحَدُكُمْ إِلَى الْغَائِطِ فَلْيَذْهَبْ مَعَهُ بِثَلاَثَةِ أَحْجَارٍ يَسْتَطِيبُ بِهِنَّ فَإِنَّهَا تُجْزِئُ عَنْهُ  

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