He wiped his ears inside and outside. Hisham adds: He inserted his fingers in the ear-holes. (Using translation from Abū Dāʾūd 123)   

رَأَيْتُ رَسُولَ اللهِ ﷺ تَوَضَّأَ قَالَ وَمَسَحَ بِأُذُنَيْهِ بَاطِنِهِمَا وَظَاهِرِهِمَا زَادَ هِشَامٌ أَدْخَلَ أُصْبُعَيْهِ فِي صِمَاخَيْ أُذُنَيْهِ  

[Machine] The Prophet ﷺ performed ablution and then inserted his fingers into his ears, as reported by Al-Husayn ibn Muhammad Al-Faqih, who narrated from Abu Bakr Muhammad ibn Bakr, who narrated from Abu Dawud, who narrated from Ibrahim ibn Sa'id, who narrated from Wakii', who narrated from Al-Hasan ibn Salih, who narrated from Abdullah ibn Muhammad ibn 'Aqil, who mentioned it in this way and said, "He inserted his fingers into the openings of his ears."  

أَنَّ النَّبِيَّ ﷺ تَوَضَّأَ فَأَدْخَلَ أُصْبُعَيْهِ فِي أُذُنَيْهِ 307 وَأنبأ الْحُسَيْنُ بْنُ مُحَمَّدٍ الْفَقِيهُ ثنا أَبُو بَكْرٍ مُحَمَّدُ بْنُ بَكْرٍ ثنا أَبُو دَاوُدَ ثنا إِبْرَاهِيمُ بْنُ سَعِيدٍ ثنا وَكِيعٌ ثنا الْحَسَنُ بْنُ صَالِحٍ ثنا عَبْدُ اللهِ بْنُ مُحَمَّدِ بْنِ عَقِيلٍ فَذَكَرَهُ بِنَحْوِهِ وَقَالَ أُصْبُعَيْهِ فِي جُحْرَيْ أُذُنَيْهِ