It was narrated from 'Abdullah bin Abi Qatadah that his father said:"The Messenger of Allah (ﷺ) said: 'When any one of you enters Al-Khala' (the toilet), let him not touch his penis with his right hand
ReferencesSunan an-Nasa'i 25In-book: Book 1, Hadith 25Source: hadith-api (fawazahmed0)