"When you clean yourselves (with stones, after defecating), use an odd number."
Sunan an-Nasa'i Book 1, Hadith 43
← Previous Hadith "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.

Sunan an-Nasa'i Book 1, Hadith 42 Next Hadith → "When any one of you goes to the Gha'it (toilet to defecate), let him take with him three stones and clean himself with them, for that will suffice him."

Sunan an-Nasa'i Book 1, Hadith 44