Volume 7 · Book 62 · Hadith 12
Narrated Sad bin Abi Waqqas: The Prophet prevented 'Uthman bin Mazun from that (not marrying), and had he allowed him, we would have got ourselves castrated.(1)
— Sahih Bukhari, Volume 7, Book 62: Wedlock, Marriage (Nikaah), Hadith #12