It is narrated from Sayyiduna Salman (may Allah be pleased with him) that the polytheists said to him: "We see that your companion (the Prophet, peace and blessings be upon him) teaches you even the manner of sitting to relieve yourselves!" He said: Yes. Indeed he forbade us that any of us should clean himself with his right hand or face the qiblah, and he forbade us dung and bones, and he (peace and blessings be upon him) said: "None of you should clean himself with fewer than three stones."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 545