وعنها قالت: كانت يد رسول الله صلى الله عليه وسلم، اليمنى لطهوره وطعامه، وكان اليسرى لخلائه وما كان من أذى. حديث صحيح
Messenger of Allah was used to using his right hand for performing Wudu and for eating his food whereas he was used to using his left hand in his toilet and for other similar purposes.
Riyad as-Salihin 721, Book 2, The Book of Good Manners, Hadith 42. 1 min read