Mishkat al-Masabih 3 Purification كتاب الطهارة 29

وَعَن عَلِيٍّ قَالَ: سَأَلَتْ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ الْمَذْيِ فَقَالَ: «مِنَ الْمَذْيِ الْوُضُوءُ وَمِنَ الْمَنِيِّ الْغسْل» . رَوَاهُ التِّرْمِذِيّ

‘Ali said: I asked the Prophet about prostatic fluid and he replied, “For prostatic fluid ablution is necessary, but for seminal emission washing.” Tirmidhi transmitted it.