Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "I am to you like a father. When one of you goes to relieve himself, he should neither face the qiblah nor turn his back to it, and when he cleans himself, he should not do so with his right hand." And he (peace and blessings be upon him) used to command (the use of) three stones and forbid dung and decayed bone.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 431