It was narrated that Marwan bin Al-Hakam said that one should perform Wudu' after touching one's penis. Marwan said:

"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.'"

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ، عَنْ مَرْوَانَ بْنِ الْحَكَمِ، أَنَّهُ قَالَ الْوُضُوءُ مِنْ مَسِّ الذَّكَرِ فَقَالَ مَرْوَانُ أَخْبَرَتْنِيهِ بُسْرَةُ بِنْتُ صَفْوَانَ . فَأَرْسَلَ عُرْوَةُ قَالَتْ ذَكَرَ رَسُولُ اللَّهِ ﷺ مَا يُتَوَضَّأُ مِنْهُ فَقَالَ " مِنْ مَسِّ الذَّكَرِ " .