It was narrated that 'Ali said:
"I said to Al-Miqdad: 'If a man is intimate with his wife and excretes prostatic fluid but does not have intercourse - ask the Prophet (ﷺ) about that, for I am too shy to ask him about it since his daughter is married to me.' So he asked him, and he said: 'Let him wash his male member and perform Wudu' as for Salah.'"
English reference: Vol. 1, Book 1, Hadith 153
Arabic reference: Book 1, Hadith 154