Sayyiduna al-Miqdam bin Ma'dikarib (may Allah be pleased with him) says: I saw the Messenger of Allah (peace and blessings be upon him) performing ablution. (Then, describing the manner of ablution,) he said: He (peace and blessings be upon him) wiped the outer and inner parts of his ears.
Hisham (may Allah have mercy on him) added these words: He (peace and blessings be upon him) inserted his fingers into the holes of his ears.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 305
It is narrated from Rubayyi' bint Mu'awwidh bin Afra' (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) performed ablution and inserted his fingers into his ears.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 306
Abdullah bin Muhammad bin Aqil (may Allah have mercy on him) narrated a report like the previous hadith, and said: His (peace and blessings be upon him) fingers were in the holes of his ears.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 307