Musannaf Ibn Abi Shayba 1:1710

Waki’ narrated to us, from Zam’ah ibn Salih, from ‘Isa ibn Yazdad, from his father, that he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "If one of you urinates, let him flick his private part three times." Zam’ah said: "For that is sufficient for him."