Book 50, Hadith 57

It was narrated from Shutair bin Shakal bin Humaid, that his father said:"I said: 'O Messenger of Allah, teach me a supplication from which I may benefit.' He said: 'Say: Allahumma 'afini min sharri sam'i, wa basari, wa lisani, wa qalbi, wa sharri mani (O Allah, protect me from the evil of my hearing, my seeing, my tongue and my heart, and the evil of my sperm.)" - Meaning his sexual organ