Musnad Abu Ya'la al-Mawsili 228:5

Muhammad ibn al-Khattab narrated to us, al-Jaddi narrated to us, Shu'bah informed us, from Sa'd ibn Ibrahim, who said: I heard Muhammad ibn 'Abd al-Rahman ibn Thawban narrating from a man of the Ansar, from a man among the Companions of the Prophet, may Allah bless him and grant him peace, from the Prophet, may Allah bless him and grant him peace, who said: "Three things are a duty upon every Muslim on the day of Friday: the tooth-stick (siwak), bathing (ghusl), and perfume, if he finds it."