Sunan Ibn Majah, Hadith 441 ⓘ
It was narrated that Rubai' bint Mu'awwidh bin 'Afra' said: "The Prophet performed ablution, and he put his fingers in the (holes) inside of his ears."
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَعَلِيُّ بْنُ مُحَمَّدٍ، قَالاَ حَدَّثَنَا وَكِيعٌ، عَنِ الْحَسَنِ بْنِ صَالِحٍ، عَنْ عَبْدِ اللَّهِ بْنِ مُحَمَّدِ بْنِ عَقِيلٍ، عَنِ الرُّبَيِّعِ بِنْتِ مُعَوِّذِ ابْنِ عَفْرَاءَ، قَالَتْ تَوَضَّأَ النَّبِيُّ ـ صلى الله عليه وسلم ـ فَأَدْخَلَ إِصْبَعَيْهِ فِي جُحْرَىْ أُذُنَيْهِ .
also referenced under: Book 1, Hadith 476 (In-Book) & Volume 1, Book 1, Hadith 441 (DarusSalam)