Sayyiduna Salman (may Allah be pleased with him) said: A man from among the polytheists said to me: By Allah! I see that your companion teaches you everything, even the etiquette of relieving yourselves! I said: Yes, "He forbade us from facing the qiblah while relieving ourselves, from cleaning ourselves (istinja) with our right hands, from cleaning ourselves with fewer than three stones, and from cleaning ourselves with dung or a bone."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6055