"If any one of you touches his private part with his hand, let him perform Wudu'."  

أَنَّ النَّبِيَّ ﷺ قَالَ إِذَا أَفْضَى أَحَدُكُمْ بِيَدِهِ إِلَى فَرْجِهِ فَلْيَتَوَضَّأْ  

"Busrah bint Safwan told me that." 'Urwah sent someone to check that, and she said: "The Messenger of Allah ﷺ mentioned what Wudu' is done for, and said: 'Touching the penis.'"  

مَرْوَانُ أَخْبَرَتْنِيهِ بُسْرَةُ بِنْتُ صَفْوَانَ فَأَرْسَلَ عُرْوَةُ قَالَتْ ذَكَرَ رَسُولُ اللَّهِ ﷺ مَا يُتَوَضَّأُ مِنْهُ فَقَالَ مِنْ مَسِّ الذَّكَرِ  

"Whoever touches his penis, he should not perform Salah until he performs Wudu'." Abu 'Abdur-Rahman (An-Nasa'i) said: Hisham bin 'Urwah did not hear this Hadith from his father.  

أَنَّ النَّبِيَّ ﷺ قَالَ مَنْ مَسَّ ذَكَرَهُ فَلاَ يُصَلِّي حَتَّى يَتَوَضَّأَ قَالَ أَبُو عَبْدِ الرَّحْمَنِ هِشَامُ بْنُ عُرْوَةَ لَمْ يَسْمَعْ مِنْ أَبِيهِ هَذَا الْحَدِيثَ وَاللَّهُ سُبْحَانَهُ وَتَعَالَى أَعْلَمُ