The Book of Purification
1/23. Chapter:
The Prohibition Of Touching One's Penis With the Right Hand When Relieving Oneself
Sunan an-Nasai
أَخْبَرَنَا هَنَّادُ بْنُ السَّرِيِّ، عَنْ وَكِيعٍ، عَنْ هِشَامٍ، عَنْ يَحْيَى، - هُوَ ابْنُ أَبِي كَثِيرٍ - عَنْ عَبْدِ اللَّهِ بْنِ أَبِي قَتَادَةَ، عَنْ أَبِيهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا دَخَلَ أَحَدُكُمُ الْخَلاَءَ فَلاَ يَمَسَّ ذَكَرَهُ بِيَمِينِهِ " .
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.'"
Reference : Sunan an-Nasa'i 25In-book reference : Book 1, Hadith 25English translation : Vol. 1, Book 1, Hadith 25