Narrated Aisha, Ummul Mu'minin:

The Messenger of Allah ﷺ said: Ten are the acts according to fitrah (nature): clipping the moustache, letting the beard grow, using the tooth-stick, cutting the nails, washing the finger joints, plucking the hair under the arm-pits, shaving the pubes, and cleansing one's private parts (after easing or urinating) with water. The narrator said: I have forgotten the tenth, but it may have been rinsing the mouth.

حَدَّثَنَا يَحْيَى بْنُ مَعِينٍ، حَدَّثَنَا وَكِيعٌ، عَنْ زَكَرِيَّا بْنِ أَبِي زَائِدَةَ، عَنْ مُصْعَبِ بْنِ شَيْبَةَ، عَنْ طَلْقِ بْنِ حَبِيبٍ، عَنِ ابْنِ الزُّبَيْرِ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ ﷺ
" عَشْرٌ مِنَ الْفِطْرَةِ قَصُّ الشَّارِبِ وَإِعْفَاءُ اللِّحْيَةِ وَالسِّوَاكُ وَالاِسْتِنْشَاقُ بِالْمَاءِ وَقَصُّ الأَظْفَارِ وَغَسْلُ الْبَرَاجِمِ وَنَتْفُ الإِبِطِ وَحَلْقُ الْعَانَةِ وَانْتِقَاصُ الْمَاءِ " . يَعْنِي الاِسْتِنْجَاءَ بِالْمَاءِ . قَالَ زَكَرِيَّا قَالَ مُصْعَبٌ وَنَسِيتُ الْعَاشِرَةَ إِلاَّ أَنْ تَكُونَ الْمَضْمَضَةَ .