It was narrated from 'Abdullah bin Mas'ud, that the Messenger of Allah ﷺ forbade cleaning oneself with bones or dung. (Using translation from Nasāʾī 39)  

أَنَّ رَسُولَ اللهِ ﷺ «نَهَى أَنْ يَسْتَطِيبَ أَحَدُكُمْ بِعَظْمٍ أَوْ رَوْثٍ»  

[Machine] The Messenger of Allah ﷺ said, "Do not cleanse yourselves with dung or bones, for they are provisions for your brothers from among the jinn."  

قَالَ رَسُولُ اللهِ ﷺ «لَا تَسْتَنْجُوا بِالرَّوْثِ وَلَا بِالْعِظَامِ فَإِنَّهَا زَادُ إِخْوَانِكُمْ مِنَ الْجِنِّ»