عَنْ سَهْلِ بْنِ حُنَيْفٍ رَضِيَ اللَّهُ عَنْهُ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ بَعَثَهُ قَالَ أَنْتَ رَسُولِي إِلَى أَهْلِ مَكَّةَ قُلْ إِنَّ رَسُولَ اللَّهِ أَرْسَلَنِي يَقْرَأُ عَلَيْكُمُ السَّلَامَ وَيَأْمُرُكُمْ بِثَلَاثٍ لَا تَحْلِفُوا بِغَيْرِ اللَّهِ وَإِذَا تَخَلَّيْتُمْ فَلَا تَسْتَقْبِلُوا الْقِبْلَةَ وَلَا تَسْتَدْبِرُوهَا وَلَا تَسْتَنْجُوا بِعَظْمٍ وَلَا بِبَعَرَةٍ
It is narrated from Sayyiduna Sahl bin Hunaif (may Allah be pleased with him), he says: The Noble Prophet (peace and blessings be upon him) sent me and said: You are my envoy to the people of Makkah. Tell them: The Messenger of Allah has sent me to you, he (peace and blessings be upon him) conveys his greetings to you and commands three things: (1) Do not swear by anyone other than Allah, (2) When relieving yourself, neither face the Qiblah nor turn your back towards it, and (3) Do not use bones or dung for istinja (purification).