It is stated in this hadith that he (peace and blessings be upon him) "wiped his ears by inserting both his index fingers (into them), and with his thumbs (he wiped) from the opposite side, and so he wiped the outer and inner parts of his ears." Hasan; Ibn Hibban recorded it: [1086].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 316