Riyad as-Salihin, Book 2, Hadith 722 (In-Book) ⓘ
'Aishah (May Allah be pleased with her) reported: 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.[Abu Dawud]
وعنها قالت: كانت يد رسول الله صلى الله عليه وسلم ، اليمنى لطهوره وطعامه، وكان اليسرى لخلائه وما كان من أذى. حديث صحيح، ((رواه أبو داود وغيره بإسناد صحيح)).