Mishkat al-Masabih 3081
Sa'd b. Abu Waqqas said:
God’s Messenger objected to ‘Uthman b. Maz’un living in celibacy. If he had given him permission we would have had ourselves castrated. 

(Bukhari and Muslim.)
وَعَنْ سَعْدِ بْنِ أَبِي وَقَّاصٍ قَالَ: رَدَّ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَلَى عُثْمَان ابْن مَظْعُونٍ التَّبَتُّلَ وَلَوْ أَذِنَ لَهُ لَاخْتَصَيْنَا