Sahih Ibn Khuzaymah

It is narrated from Sayyidah Aisha (may Allah be pleased with her) that the Prophet Muhammad (peace and blessings be upon him) said: "Ten acts are from the natural disposition (fitrah): trimming the mustache, putting water into the nose (and cleaning it), using the miswak, letting the beard grow, plucking the armpit hair, removing the pubic hair, performing istinja (cleaning oneself after relieving oneself), (or sprinkling water on the private part after ablution), trimming the nails, and washing the joints of the fingers." In his narration, Abda says: I do not know what the tenth act is, except that it might be rinsing the mouth. In Waki’s narration, Mus’ab said: I forgot the tenth act, perhaps it is rinsing the mouth. Waki’ says: « اِنتقَاصُ الْمَاءَ » "The reduction of water" means that when one sprinkles water on his private part, the drops of urine will stop coming out. (The Imam says) Ibn Rafi’ and Sufyan did not mention the tenth act, nor did they mention it while expressing doubt.