The Messenger of Allah ﷺ said, "Ten things are part of the natural disposition: trimming the moustache, letting the beard grow, using the tooth-stick, rinsing water into the nose, clipping the nails, washing the finger joints, plucking the underarm hair, shaving the pubic hair, and cleansing with water," meaning istinja.Zakariya said, Musab said, "I have forgotten the tenth, unless it is rinsing the mouth."
حدثنا وكيع قال حدثنا زكريا بن أبي زائدة عن مصعب بن شيبة عن طلق بن حبيب عن ابن الزبير
قال رسول الله ﷺ عشر من الفطرة قص الشارب وإعفاء اللحية والسواك واستنشاق بالماء وقص الأظفار وغسل البراجم ونتف الإبط وحلق العانة وانتقاص الماء يعني الاستنجاء قال زكريا قال مصعب ونسيت العاشرة إلا أن تكون المضمضة
Its chain of transmission is sahih. Musab bin Shayba is trustworthy, and his hadith is found in Muslim.This hadith was narrated by Muslim 1/323 no. 261, Abu Dawud 1/14 no. 53, Ibn Majah 1/107 no. 293, and Ibn Khuzayma 1/47 no. 88, all of them in the Book of Purification, and by Tirmidhi 5/91 no. 2757 in the Book of Manners, where he graded it hasan, and by Nasai 8/126 no. 5040 in the Book of Adornment.