Hisham bin 'Abdul Malik al-Tayalasi هشام بن عبد الملك أبو الوليد الطيالسي · The Book of Purification

"I was one who had a lot of prostatic discharge, so I asked the Prophet (ﷺ) and he said: 'If you see Madhi (prostatic fluid) then perform Wudu' and wash your penis, but if you see semen ejaculated, then perform Ghusl.'"