"Allah's Messenger went out to relieve himself. So he said: 'Bring me tree stones.'" He said, "So I came with two stones and a piece of dung. So he took the two stones, and left the dung. He said: 'It is Riks (a degenerative or filthy thing)."
Jami` at-Tirmidhi Book 1, Hadith 17
← Previous Hadith "They said to Salman, 'Your Prophet taught you about everything, even defecating?' So Salman said, 'Yes. He prohibited us from facing the Qiblah when defecating and urinating, performing Istinja with the right hand, using less than three stones for Istinja, and using dung or bones for Istinja"

Jami` at-Tirmidhi Book 1, Hadith 16 Next Hadith → Allah's Messenger said: "Do not perform Istinja, with dung, nor with bones. For indeed it is provisions for your brothers among the Jinn."

Jami` at-Tirmidhi Book 1, Hadith 18