(1) The Book of Purification
كتاب الطهارة
(112) Chapter: What Invalidates Wudu' And What Does Not Invalidate Wudu' Of Madhi (Prostatic Fluid)
(112) باب مَا يَنْقُضُ الْوُضُوءَ وَمَا لاَ يَنْقُضُ الْوُضُوءَ مِنَ الْمَذْىِ
Sunan an-Nasa'i 154 
It was narrated from 'A'ish bin Anas that 'Ali said:
"I was a man who had a lot of prostatic discharge, so I told 'Ammar bin Yasir to ask the Messenger of Allah (ﷺ) (about it) because his daughter was married to me. He said: 'Wudu' is sufficient for that.'"
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ عَطَاءٍ، عَنْ عَائِشِ بْنِ أَنَسٍ، أَنَّ عَلِيًّا، قَالَ كُنْتُ رَجُلاً مَذَّاءً فَأَمَرْتُ عَمَّارَ بْنَ يَاسِرٍ يَسْأَلُ رَسُولَ اللَّهِ صلى الله عليه وسلم مِنْ أَجْلِ ابْنَتِهِ عِنْدِي فَقَالَ ‏ "‏ يَكْفِي مِنْ ذَلِكَ الْوُضُوءُ ‏"‏ ‏.‏
Grade :  Hasan (Darussalam)
Reference : Sunan an-Nasa'i 154
In-book reference : Book 1, Hadith 155
English translation : Vol. 1, Book 1, Hadith 154