It was narrated that 'Uqbah bin Suhban said:
"I heard 'Uthman bin 'Affan say: 'I never sang a song or told a lie or touched my penis with my right hand after I swore on oath of allegiance to the Messenger of Allah to that effect.'" (RU)
English reference (RU): Vol. 1, Book 1, Hadith 311 (RU)
Arabic reference (RU): Book 1, Hadith 332 (RU)