Urwa reported, "I went in to see Marwan bin Hakam, and we discussed what requires ablution."Marwan said, "And whoever touches his penis."Urwa replied, "I did not know that."Marwan said, "Busra bint Safwan informed me that she heard the Messenger of Allah ﷺ say, 'Whoever touches his penis must perform ablution.'"
حدثنا عبد الله بن مسلمة عن مالك
أنه سمع عروة يقول دخلت على مروان بن الحكم فذكرنا ما يكون منه الوضوء فقال مروان ومن مس الذكر فقال عروة ما علمت ذلك فقال مروان أخبرتني بسرة بنت صفوان أنها سمعت رسول الله ﷺ يقول من مس ذكره فليتوضأ
[Sahih] Reported by Nasai in the Book of Purification, chapter, "Wudu after touching the penis," hadith no. 163, from the hadith of Malik through this chain, and it is also found in Muwatta (narration of Yahya) 1/42, narration of Qanabi, p. 50. Ibn Mulaqqin graded it sahih in Tuhfat al-Muhtaj 1/151, hadith no. 25, saying, "The four [imams] reported it with a sound chain that has no grounds for criticism."