"The Prophet ﷺ wanted to defecate, and he told me to bring him three stones. I found two stones and looked for a third, but I could not find any, so I picked up a piece of dung and brought them to the Prophet ﷺ. He took the two stones and three away the dung and said: "This is Riks." Abu 'Abdur-Rahman (An-Nasai') said: Riks is the food of the jinn.  

أَنَّهُ سَمِعَ عَبْدَ اللَّهِ يَقُولُ أَتَى النَّبِيُّ ﷺ الْغَائِطَ وَأَمَرَنِي أَنْ آتِيَهُ بِثَلاَثَةِ أَحْجَارٍ فَوَجَدْتُ حَجَرَيْنِ وَالْتَمَسْتُ الثَّالِثَ فَلَمْ أَجِدْهُ فَأَخَذْتُ رَوْثَةً فَأَتَيْتُ بِهِنَّ النَّبِيَّ ﷺ فَأَخَذَ الْحَجَرَيْنِ وَأَلْقَى الرَّوْثَةَ وَقَالَ هَذِهِ رِكْسٌ قَالَ أَبُو عَبْدِ الرَّحْمَنِ الرِّكْسُ طَعَامُ الْجِنِّ