The Messenger of Allah's ﷺ left hand was for the toilet and anything unclean, while his right hand was for his ablution and his food.
حدثنا محمد بن جعفر عن سعيد عن أبي معشر عن النخعي
كانت يد رسول الله ﷺ اليسرى لخلائه وما كان من أذى وكانت اليمنى لوضوئه ولمطعمه