Hadith
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّهُ كَانَ يَقُولُ مَنْ مَسَّ ذَكَرَهُ فَقَدْ وَجَبَ عَلَيْهِ الْوُضُوءُ .
Yahya related to me from Malik from Hisham ibn Urwa that his father used to say, "If any of you touches his penis he has to do wudu
Sahih · Salim al-Hilali
Muwatta Malik 92 ·Book 2, Hadith 61·Also available on sunnah.com·