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