Sahih Muslim | Book 8 | Hadith Number 3237

Narrated by Sa'd b. Abi Waqqas
Sa'd b. Abi Waqqas (Allah be pleased with him) reported: The Messenger of Allah (may peace be upon him) rejected (the idea) of Uthman b. Muz' un-living in celibacy (saying): And if he (the Holy Prophet) had given me permission We would have got ourselves castrated.