Abu Huraira (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "I am like a father to you. When any of you goes to relieve himself, he should neither face the Qiblah nor turn his back towards it, and he commanded to perform istinja with three stones, and forbade using dung and bones for istinja, and forbade a man from performing istinja with his right hand."
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 33
Hadith Takhrijأخرجه أبو داود: الطهارة، باب كراهية استقبال القبلة عند قضاء الحاجة (8)، وابن ماجة: الطهارة، باب الاستنجاء بالحجارة والنهي عن الروث والرمة (313) - وصححه ابن خزيمة: 80.