Musnad Ahmad 1153:1042

Waki’ narrated to us, he said: Zakariya ibn Abi Za’idah narrated to us, from Mus’ab ibn Shaybah, from Talq ibn Habib, from Ibn al-Zubayr, from ‘Aishah, she said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Ten are of the natural disposition (fitrah): trimming the mustache, letting the beard grow, using the siwak, inhaling water (into the nose), clipping the nails, washing the knuckles, plucking the armpit hair, shaving the pubic hair, and using water for purification," meaning cleaning oneself after relieving oneself. Zakariya said: Mus’ab said: And I forgot the tenth, unless it is rinsing the mouth.